The 'joke' was not even a joke in the context it was told. It was an example of regressive/reductionist attitudes of the past and present, which he is trying to break down for teaching's sake. Does he want his students to simply hear the words he has to say on the subject or to engage intellectually with the lecture? Uncomfortable challenges are part of any successful curriculum.

Now, if you mean 'should he have known better than to assume no one would get ludicrously bent out of shape about it,' then maybe I agree.....but the most pugnacious reactions to his 'joke' are completely off the wall in their illogic. About what you might expect from intelligent college kids whose brains haven't quite fully developed yet.