"To stop the bombing, we have to repeal 'gay'" will be argued on the Senate floor? Is that what you're suggesting?
First, you're not using the same logic that the Right Wing nut jobs use. Your logic is... logical. Their logic is fanatical, religion based, and ideological. True logic plays no part in their thinking.
Second, such anti-gay terror attacks would bolster the Right's argument that the American people do not approve of gay civil rights and same-sex marriage. These, they argue, are the result of activist courts, that flaunt the will of the people in a democracy. And so therefore the people have risen up to reject them, in an exercise of democratic principles (small letter "d').
Crazy as it may sound, that's how these crazies think. And if nothing else, acts of violence against gays become acts of revenge, expressing personal rage & hatred. So yes, I would expect to see incidents of anti-gay terrorism as a result of gay discrimination being declared unconstitutional by the courts, and made illegal by legislative bodies.