Let us begin with this fact: The left always suppresses speech. Since Vladimir Lenin and the Bolshevik Revolution in Russia in 1917, there has been no example of the left in control and not crushing dissent.
That is one of the important differences between liberal and left: Liberalism and liberals believe in free speech. (The present leftist threat to freedom in America, the greatest threat to freedom in American history, is made possible because liberals think they have more to fear from conservatives than from the left. Liberals do not understand that the left regards liberals as their useful idiots.)
The left controls universities. There is little or no dissent allowed at universities.