Ben Levi: of course the Rambam is talking about “aggadata” in general. I realize that. However, the reason why he calls the people who will dismiss “maamorei chazal” fools is because they dismiss chazal totally!!! The Rambam tells us that , as unusual a chazal is, there are underlying, mystic understandings and explanations. The Rambam does not say that you have to accept “maamorie chazal”as they are written! Quite the contrary. That is the approach of the first group, whom he calls very simple people!
Rabbi Slifkin ,and others, have discussed “maamorei chazal” that contradict science and obvious reality. That is not what the Rrambam discusses in the “pirush hamishneh’ that you pointed to.
BTW-if you have any interest, on Rabbi Slifkin’s website (not himslef) there is a very erudite discussion specifically on this issue!