Let's play an intellectual game. Is it possible to imagine a sensible reason for Eich to hold the view he and others hold? If you are unable to imagine such a reason, it is because you are misunderstanding that position.
The Principle of Charity [1] says you should assume your ideological opponents' beliefs must make sense from their perspective. If you can’t even conceive of a position you oppose being tempting to someone, you don’t understand it and are probably missing something. You might be missing a strong argument that the position is correct. Or you might just be missing something totally out of left field.
I propose most people in this thread -- and indeed in the San Francisco-based startup culture -- do not understand the position Eich holds. And it does not hold to the Principle of Charity, choosing instead to ostracize and boycott and demonize with ugly labels.
Perhaps a fair way to approach this debate would be, "Assuming Eich does not hate gay people, why would he be opposed to redefining marriage?"
