Does political diversity need to be protected by law?

In light of the venom of faculty members and mob violence against conservatives at Michigan Glenn Reynolds asks:

If I were a Republican — or even Republican-curious — student at the University of Michigan, I’d feel unwelcome there. If I were a Republican governor or legislator in Michigan, and I think they have some of those, I’d be finding ways to encourage Michigan to be more inclusive and diverse. Especially given that — perhaps because of incitement caused by faculty views such as those above — the University of Michigan has already seen mob violence against conservatives. Perhaps Michigan lawmakers need to add political discrimination to their state’s civil rights code — at least as relates to institutions of education — especially in light of Cass Sunstein’s recent argument that political hatred is a serious problem in our society.