So, the exact complaint against Horowitz was what? What he said or the fact he was attempting to speak? It appears from the video of the event, the protest was against the content.
The Left loves to scold the rest of us when we object to something they are presenting on television or National Public Radio. Their standard answer is, if you don’t like it you are free to change the channel. In other words, if you are standing in an area where someone is saying something you disagree with, you are free to leave.
Well, these people were free to leave when Horowitz was speaking, but instead of extending to him what they demand of the rest of us, they made it impossible for him to speak.
Free speech is dead on this campus.
As to the dangers, the protesters made his point for him.