Ben levi and others: I don’t know Rabbi Meiselman and he certainly may be a big,very big talmid chochom. However, I’ll eat my hat if he knows more about zoology than rabbi Slifkin. (see Shofon). Dotti for astronomy.
The underlying argument is whether maamorei chazal that are not halachically based-in other words, aggadata- are binding on us and we must acccept them blindly(see R’Elya Ber Wachtfogel and others). This view has become popular recently but it was never accepted by many rishonim and acharonim. To say-as PbA says- that one is a “kofer” if one does not believe in aggadata is false and has contributed to the radicalization of yiddishkeit. The opposite argument, that we are only bound by halacha,not aggadata- is, in essence, what rabbi Slifkin is relying upon.