We don't know what Eich supports or opposes, all we know is that he contributed money to a campaign to oppose a particular law. Maybe he thought the law was unconstitutional or that, as written, it would cause more harm than good.
And even if he were opposed to gay marriage, if you cannot imagine how someone can philosophically oppose something, even if they are wrong, and yet still practice tolerance for that thing in their own life, then you cannot be reasoned with and should probably delete your account.
