You should, and are, free to express those opinions but bigotry is not a protected class. Your employer should be free to fire you if it doesn't like what you are saying.
What value does tenure provide in this scenario? His blog is not related to CS or academia. He is doing harm to the reputation of the university and CS department.
Well thats where we disagree i guess. When people google University of Montana computer science and see the dozens of articles that pop up about this guy they are not going to think oh yay this school is a champion of intellectual freedom. They are going to see a tenured professor propping up the worst of the worst CS stereotypes and software engineering bro culture.
In a college environment is probably the most socially safe (i.e. distinct from propagandizing) and productive (i.e. more likely to be intellectually examined) environments for them.
So if they exist anywhere, and I subscribe to the idea that unpopular things need to be speakable somewhere, then college is a good place.