Diversity as a concept cannot legitimately be defined to include intolerance as an attribute to be protected. Swap out "anti-gay-marriage" for "racist" or "anti-semitic" – it would be difficult to argue that calling for the resignation of an active campaigner against racial equality was "anti-diversity"; the same applies here.
Not sure if you're a member of the LGBT community or not, but it sounds like your argument here is that because the reactions of others against Prop 8 were stronger than your own, they were invalid.
It's not a very tenable position to take. Do you really believe the outcry over putting minorities in prison would parallel that of Prop 8?
No, I don't think they're invalid, I just think such strong visceral reactions are counterproductive. Prop 8 supporters and/or fence sitters are much less likely to have an open mind when someone is screaming at them that they're a bigot.
I've not seen any evidence of that, and I don't see what your point is. I mean, it did actively strip civil rights from LGBT people, and that's pretty bad…