Does the university then have to "enforce" diversity in all its events? Though I understand the point of diversity, but enforcing it might hurt more than it help.
Well, one of the purposes of an institute of higher learning is to provide opportunities for education. By cancelling and even that appears to promote a troubling status quo, they are both explicitly and visibly not condoning that status quo and at the same time providing an opportunity for those with a quick enough wit to benefit from a raised awareness of the problems of others.
Of course, they're not required to do such a thing, and obviously the learning opportunity is lost on some. Nevertheless, just having the conversation may have made one tiny change somewhere, and with enough such conversations and changes, inexorable progress gets made.