Recent protests and in some cases riots by left wing extremists and "Black Lives Matter" protesters that infringe on the free speech of others should not be tolerated let alone seemingly encouraged by institutions of higher learning.
Blocking people from attending planned events to the extent the police say it's dangerous for people to attend inhibits free speech.
Hold up signs. Yell as people enter. Attend and ask questions. Maybe even disrupt the speaker and be peacefully escorted out of the event. These are all constitutionally protected forms of free speech.
Preventing the event from happening by blocking the doors or rioting is NOT protected by the the constitution and frankly those that do this should be prosecuted.