It is my assumption that the University of Saint Louis is a government owned and run school. That places it outside most other colleges and universities which are private. A private school can make its own laws, a government one must follow the Constitution, including the First Amendment. How that is done varies from state to state, and even jurisdictions within the state.
Putting information or flyers on a desk before class time is one thing. Doing it during class time is another. Stopping that is not an infringement of free speech, stopping the flyers/information would be.
Chris Hedges wrote about a teacher looking the door at a certain time, perhaps that would be allowed in Saint Louis, perhaps not.
The other side of the coin is, that no other country protects the freedom of any individual to think and say anything, to the degree the U.S. does. There are very few limitations on it, purposely so that the public will be free to both hear and choose for itself whether to consider such ideas seriously or not. Outside of not calling for the overthrow of the government by violent means, or encouraging people to go and do some violent act, or using “fighting words”, everything else is open under the Constitution.
Perhaps that is why the founders thought a free and informed and virtuous public was needed to make the Republic run smoothly and safely. “The very purpose of the First Amendment is to foreclose public authority from assuming a guardianship of the public mind through regulating the press, speech and religion,” Justice Jackson wrote in 1945. “In this field, every person must be his own watchman for truth, because the forefathers did not trust any government to separate the true from the false for us.”
That puts a heavy burden on all of us. Having to listen to something that attacks us, is difficult at best, but trusting government to control it, is just so much worse. That way can lead to an end to speech that the government deems mean or hateful. What that might be would depend on who was in charge of the government, for me, under Obama one thing, under Trump another, a free for all is better,in my view than managed thought.