The supreme court has equated financial contribution with speech, and many of us agree with that position.

Therefore, we can only see this as an attempt to ostracize and attack anyone who speaks to the opposite side. This action is chilling on speech, which is exactly what the OP was talking about. Just because you don't see it that way, doesn't mean it isn't, and won't be perceived by others that way.

I think proposition 8 was the wrong thing, promoted for bad reasons and on the wrong side of where society needs to be, but I also happen to feel that this attempt to quash any possibility of opposing free speech by ensuring to mob anyone who rises to the top having once taken a view we don't agree with as far more dangerous and harmful for our society than prop 8 could ever have been. It enforces positions without the liberty of allowing speech, and without the ability to challenge in court, as bad laws do.