Sounds like first ammendment infringement, can't be certain though. The same tactic was used on activist groups I belonged to, dumping smelly manure at protest sites is aimed at thwarting people excercising their right to assembly.
Just wait for the pepper spraying... I'll bet this turns into something similar to the UC Davis incident - school board and police under scrutiny. It's a major college campus, I thought out of the box thinking and protests are to be expected (and put up with).