My understanding is that he used the word while referring to a book that they weren’t even studying (They were studying Plato’s Republic.) To prove a point, apparently. But he certainly could have made the same point without using the explicitly offensive term.
That’s apparently a thing among some “conservative” professors; say something potentially offensive and hurtful without regard to (or potentially because of) its impact on students. Why? Because they can, I guess, according to the school’s “free speech” principles.
More on the controversy.
@Aquamarine99 I’m not sure I would expect the ratio of outspoken conservative professors in CMC’s government department to “shift drastically” over the years. Many of them aren’t that old. Nadon included.