He's a professor, so he should teach diversity of thought and critical thinking. That's what the Humanites used to teach since the Age of Enlightment, but unfortunaltey it's fading away, these days, under the pressure of PC trends.
PC is not a nice ideology that wants better things for the world, it's a coercion that is used to exert moral power. So, naturally, the proponents of this trend (like this professor) will criminalize different opinions (or at least they will forbid them).