discrimination against homosexuals is forbidden both by California state law and by Stanford's own governing policies.
Discrimination is an action, not an opinion. Mr. Brown did not practice or even advocate discrimination against homosexuals. Mr. Chapin has in essence (and probably without realizing it) announced that just holding the opinion that homosexuality is wrong constitutes a form of discrimination against homosexuals and that the state is therefore justified in practicing real discrimination against those who hold (or anyway publicly state) such beliefs.