How is that not enough evidence? He paid $1000 to the campaign. Since the outrage began, he has said nothing to nuance his position, nothing to talk about changing his mind, nothing to make his employees or contributors feel like he had their best interest at heart.

And furthermore, are you really trying to say we should have to directly tie how that money went into the Prop 8 bank account and then was spent to influence voters in California?

You're making completely irrational requests. Showing up at an anti-civil rights protest back in the 60s may not have directly influenced someone to keep their mouth shut out of safety(and how would you prove that it did), but it has an influence and to act like because you can't directly tie it to someone is to absolve people of any past wrongdoings short of force.

Changing your mind is okay. Saying you were wrong is okay. They need to be, as society grows and matures. But the same as the risks taken by those who try to push society's opinions ahead of itself, if you lag behind you're just as likely to get hurt.