There are certain strands of critical theory and postmodernist thought which hold that all speech is an exercise of power. On this view, to talk is to coerce. On this view, too argue for or defend social injustice, or even to discuss such ideas in the classroom, is a form of violence.
If you have that view, then of course you’ll think it’s appropriate to use violence to shut down speech you dislike. Of course you’ll believe professors or campus authorities have a duty to silence “bad” speech.
After all, on this view, when you smash windows or call in the authorities, you are not initiating violence against peaceful speakers. Rather, on this view, the speakers are acting violently by speaking, and you are merely using violence in self-defense or in defense of others.
On this view, the liberal defense of free speech is a hegemonic conspiracy, an attempt by white men to rationalize and justify their power over others. Speech is violence. When others talk, they oppress you. When you shut them down, you stop them from oppressing you.
The speech-is-violence view–a view propounded by many hard left faculty in the humanities departments–makes civil discourse a form of war. Speech is a negative-sum game. When others arm themselves with arguments, you arm yourself with sticks and stones.