1) Nothing in the civil war was about slavery. Nothing. Even freeing the slaves wasn't about the slaves. Seriously. This is amply documented. Believe it or go do more research, but don't just keep disagreeing.
2) Pork? Pork? No, that wouldn't save any pro-homo legislator in most states.
Civil rights need to gain momentum at the local level. States have to prove the viability of these laws by voting for and against state constitutional amendments, having individual state supreme courts worry and tease the issues. Eventually, a stable model of gay rights will evolve, be adopted in practice by a group of states, and a consensus will bubble up from the states' laws. People at the federal level will then say, "It's time to bring the nation up to date with the new status quo." The supreme court will eventually support a challenge to gay marriage, and that will be the approximate end of it. But the federal Supreme Court very frequently (possibly always) takes into account the states' laws and states' practices regarding issues before it.
Democracies always invite tyrannies of pluralities. No one should ever vote on someone's civil rights, it's fucking obscene. But we have the system we have, and it doesn't work according to the exact wording of the constitution (inalienable, equal rights) and it doesn't work the way (most) history books describe. Instead it's organic, and it'd be painful to ask for bigger, larger central government and less control at the local level. The local level is the only place that change by the people and for the people is possible. Grassroots government. The fed eventually follows the states. But states have to break the ice, and show a model system of laws/changes which work before the more conservative people/states/feds will follow.
argh.