It's a REALLY hard course to teach. You have to focus on the basics and make sure that people understand the assumptions so they can actually solve the problems, but yes, buying into the field in the first place requires that students understand that this is NOT even remotely where the story ends. If he didn't do that, he failed as an instructor IMO. You look at the first welfare theorem of Economics (which seems to be where every single Libertarian closed the book and said "I've read enough!") and it's exceedingly clear that the set of assumptions required help us identify where and why it does not imply for a lot of things.