My answer used to be "why, if you have the truth on your side, just prove 'em wrong and move on! so much the better for your standpoint!". However, it can get extremely tedious. A stubborn student can "plausible deniability" his way into extremely metaphysical arguments, about historical revisionism and psychology, and ultimately about epistemology itself.
I think it's important to phrase the argument not as "the students want these topics to not be discussed", but instead as "the students want these topics to be included in the actually already existing list of topics we don't discuss". And then take it topic-by-topic.
This idea that student-activism is largely composed of completely irrational anti-logic zealots is a caricature.