Minor point: you speak of Prop 8 opponents, but you're talking about Prop 8 proponents. Remember they were explicitly trying to roll back rights permanently, in the California Constitution, not trying to stop a new law from passing.

Anyhow, something to consider: there were onced nuanced segregationists--there's a funny clip where Jimmy Carter's ex chief of staff said he went from being an extreme segregationist, to a moderate segregationist, to a moderate integrationist.

That viewpoint seems insane now, because with the benefit of hindsight we can't conceive of how an extreme viewpoint can be viewed as moderate if you're living within it. But thems the breaks. If someone's a bigot, they're a bigot, no matter how complicated an ideological edifice they've erected to prove they're not a bigot.