Would we be having this conversation if he actively contributed to deny interracial couples marriage? No, because that would be inappropriate in our modern society where we don't judge people based on their skin color. Sexuality is no different.
If a CEO in another company did that, and it was brought to the public's attention, there would be calls for him to step down because he didn't believe in equal rights.
If he (imaginary CEO, not Eich) were to do that, then it would create a hostile work environment for people of different skin colors because they would know that he does not support them having basic human rights.
No matter how controversial, any personal opinion of a leader about any law doesn't create a hostile work environment unless (s)he decides to. Eich didn't have any problems accepting people at Mozilla. There were plenty of statements of LGBT(pick one) people stating that Eich treated them same as anybody else.
This being said, I do think that a person of weak character would decide to create an environment hostile to people (s)he doesn't share basic beliefs with. But people with weak character don't get elected to be community leaders in general.