Isn’t it private property such that a warrant specific to a person would be needed ? Or is a statement supporting illegal activity enough for a warrant to search the entire campus and question everyone there?
The classic example of a “sanctuary” was a church. It needed to be surrounded and the people starved out. That solution for colleges is fine with me. Shut off all utilities including water. Stop all deliveries. Check everyone as they leave until the campus is empty. Use helicopters with thermal imaging equipment to be sure it is empty. Monitor for a few weeks before letting anyone back in.
As to the first query, I'm not certain, but I do believe that when one announces that they are going to commit a crime, that opens them, immediately, to possible arrest.
These people are just nuts and need to 1) grow up and stop acting like babies 2) first learn the laws of this nation prior to spouting off 3) start worrying about the future of the colleges or cities, because of the lost Federal funding coming their way.....soon!