No-one asked the dormitory head to police Halloween costumes. What actually happened was the university sent out a letter students asking them to think about whether their Halloween costumes were mocking other people, and he insisted that this was an attack on student freedom of speech because having to think about this might make them uncomfortable wearing certain costumes - and we certainly can't have student's thinking about viewpoints outside their own in ways that make them uncomfortable.

Because all the recent stuff about student freedom of speech and the importance of exposing students to viewpoints that make them uncomfortable is actually just a push by the right-wing to move universities to the right, the students who objected to this were the ones who were portrayed as being the ones who couldn't cope with views they disagreed with.