Diversity by its essence is about diversity, and hence accepting people who are opposed to diversity is antithetical to the idea of diversity. So this argument of accepting diverse viewpoints including those against diversity is non-sensical.

The idea behind diversity is not to ignore gender differences, or racial differences, but to have the belief that skill and talent exists can come from anywhere. So these viewpoints that make generalizations about people because of their gender, race etc. serve to exclude the talent that can come from the non-white/male quarter.

Now this person is probably a good engineer, but its fair to say his impact to computing will never be as great as Ada Lovelace, Anita Borg, Fei Fei Li etc. So if a viewpoint like his hinders the next Grace Hopper then firing him is a worthy price.

The thing that the anti diversity warriors fail to understand is that their viewpoints are exclusionary to a whole swath of people, so please dont expect sympathy for your opinion when your viewpoint tells some people to go away just because of their gender/race.