"And? The implication is that if Maimonides lived today and knew today's science, he would likely be even more allegorical in his approach."
I don't think it is of much value to speculate on what the Rambam would believe but, in a way, I suspect he is correct. The question can, however, serve as an introduction into my position on the Age of the Universe issues. While I'm not really into guessing what the Rambam would say, I think it is worthwhile to look at what he did say and I believe we will find a number of ideas that lend themselves to my approach.
1. Be Cautious about what you deem "Impossible"
Impossible is a very big word. The fact that you find a certain scenario or resolution improbable doesn't mean it isn't so. The Rambam warns that if one, "reject[s] things as impossible which have never been proved to be impossible, or which are in fact possible, though their possibility be very remote, then you will be like Elisha Aher; you will not only fail to become perfect, but will become exceedingly imperfect" (Guide 1:32, Freidlander page 42, emphasis mine). To conflate improbable with impossible can, or does, lead to incorrect conclusions and even heresy ח"ו .
2. Allegory doesn't solve all problems
Allegoization is, or can be, a tool. That doesn't mean it is the best one for the job or that it will always work: “A mere argument in favour of a certain theory is not sufficient reason for rejecting the literal meaning of a biblical text, and explaining it figuratively, when the opposite theory can be supported by an equally good argument” (Guide 2:25, page 199). As we have noted in What Problem? that allegory is generally not meant to supersede the pshat, and the Rambam tells us here that to do so is essentially a last resort.
Furthermore, the Rambam recognizes that one cannot allegorize away every conflict, "If, on the other hand, Aristotle had a proof for his theory, the whole teaching of Scripture would be rejected, and we would be forced to other opinions"( ibid, page 200).
3. Fundamental Principles may only be set aside by demonstrative proof
Fundamental Principles, not to be confused with Principles of Faith (the denial of which is heresy) shouldn't be allegorized away unless one has demonstrative proof (i.e. a deductive argument with premises which are certainly true) requires that they be:
I mention this lest you be deceived; for a person might some day, by some objection which he raises, shake your belief in the theory of Creation, and then mislead you; you would then adopt the theory [of the Eternity of the Universe], which is contrary to the fundamental principles of our religion, and lead to "speaking words that turn away from God." you must rather have suspicion against your own reason, and accept the theory taught by two prophets who have laid the foundation for the existing order in the religious and social relations of mankind. Only demonstrative proof should be able to make you abandon the theory of the creation; but such a proof does not exist in Nature. (ibid 2:23, page 195)I believe that this was the quote I had in mind when I wrote, "I have seen passages in the Guide that seem to go even further in restricting allegorizing." Here the Rambam goes even further. Previously it would seem that he would allow allegorizing even if another option was available as long as it did not seem as strong. When it comes to a "fundamental principle", however, the Rambam seems to agree with the general approach of Rav Sa'adia Gaon that only when there is no other reconciliation possible is allegorization (to the exclusion of the p'shat) acceptable.
In this regard I think the Rambam's words apply more broadly, that "such a proof does not exist." With demonstrative proofs being for all practical purposes philosophically impossible at this point is no trump card which can lead to uprooting the pshat in favor of allegory when it comes to fundamental principals at least.
4. It is a fundamental principle that mankind descended from one individual, Adam
Again, bear in mind the Rambam's distinction between a fundamental principle and a principle of faith, but we read, "It is one of the fundamental principles of the Law that the Universe has been created ex nihilo, and that of the human race, one individual being, Adam, was created." (Ibid 3:50, page 381) The common ancestry of mankind from Adam is a fundamental principle that should only be allegorized away because of a demonstrative proof, but not when there is an alternative even if it seems improbable.
5. Beings were formed "fully developed" at Creation
The Rambam, citing no less of an authority on Jewish belief than the Talmud writes:
Note also the saying of our Sages:When the Universe was created, all things were created with size, intellect, and beauty fully developed, i.e. everything was created perfect in magnitude and form, and endowed with the most suitable properties; thew word zibyonam (their beauty) used here has the same meaning as zebi,'glory'" (Ezek. xx. 6). Note this likewise, for it includes a principle fully established. (ibid 3:30)Now I cannot say for certain that this "principle" fully established is a "fundamental principle" but it would seem that this is an important idea in Jewish thought and the thought of the Rambam in particular.
6. One cannot ignore the miraculous when contemplating the acts of an omnipotent Creator
The Rambam writes, "Accepting the Creation, we find that miracles are possible, that Revelation is possible, and that every difficulty in this question is remove." (2:25, page 199-200). It seems almost too obvious to mention, but it seems to me that all to often the materialistic presumptions of science (i.e nature) get artificially superimposed on the inherently supernatural act of creation.
Likewise we are told that the laws of nature were not fixed until the end of the six days of creation, "All our Sages agree that this took place on the sixth day, and that nothing new was created after the close of the six days. None of the things mentioned above is therefore impossible because the laws of Nature were then not yet permanently fixed." (ibid 2:30, page 216). While I'm not sure this is necessary for my approach, per se, I think it is an idea worth keeping in mind in relation to this topic.
7. Be modest when approaching Scripture
The Rambam encouraged a cautious, conservative approach to Scripture: "You appear to have studied the matter superficially, and nevertheless you imagine that you can understand a book which has been the guide of past and present generations, when you for a moment withdraw from your lust and appetites, and glance over its content as if you were reading a historical work or some poetical composition." (1:2, page 15)
Similarly he warns, "when he is in doubt about anything, or unable to find a proof for the object of his inquiry, he must not at once abandon, reject, or deny it; he must modestly keep back, and from regard to the honour of his Creator, hesitate[from uttering an opinion] and pause." (1:32, page 43)
8. It is not productive to speculate why God would choose a certain option
The inability to determine motive in no way indicates that something didn't occur. This is so with humans and it is certainly so with God whose "ways are not our ways."
We might be asked, Why has God inspired a certain person and not another? why has He revealed the Law to one particular nation, and at one particular time? why has He commanded this, and forbidden that? why has He shown through a prophet certain miracles? what is the object of these laws? and why has He not made the commandments and the prohibitions part of our nature, if it was His object that we should live in accordance with them? We answer to all this questions: He willed it so; or, His wisdom decided so. Just as He created the world according to His will, at a certain time, in a certain form, and upon a peculiar time, so we do not know why His will or wisdom determined any of the things mentioned in the preceding question. (2:25, page 200)
9. It is contrary to Torah to concede the possibility of the Universe existing without God even if one does accept that God does actually exist
"If one would imagine that He does not exist, no other being could possibly exist." (Mishneh Torah, Yesodei HaTorah 1:2, Moznaim Translation)
Alright, that wasn't from the Guide, but it illustrates the Rambam's view nonetheless.
10. The Opinion of Chazal should be given due respect
Earlier we cited, "All our Sages agree that this took place on the sixth day, and that nothing new was created after the close of the six days. None of the things mentioned above is therefore impossible because the laws of Nature were then not yet permanently fixed." (ibid 2:30, page 216). The Rambam here emphasises the consensus of Chazal and gives it a great deal of weight.
So, while one may not find each of these ideas equally acceptable (though I believe they are generally sound) I believe they give us some important insight into the Rambam's thinking as it might pertain to our topic. And I believe following these ideas through to their logical conclusion would give much more support to the approach I favor, and hope to present soon, than to a blanket assertion of the Creation account as being an allegory.