The reason it works, in my view is because I believe in marriage equality, not in civil unions. The problem with Obama is he views civil unions as an end. The effect of McCain, who is absolutely atrocious on gay rights would be to energize the marriage equality movement. The effect of Obama would be to energize the notion that 95% equality is ok.
What I want to know though is, if some state decided to give interracial and minority (opposite sex) couples civil unions identical to what Obama wants to give gay couples, but reserved marriage only for white couples would that be constitutional in Obama's worldview? As I said, McCain is bad for gay rights today, Obama is bad for gay rights tomorrow.
Xisiqomelir - This has been hashed to death pretty much, but the gay rights movement depends on energy, it really is a bottom up movement. With Obama pushing civil unions as an end, should he get elected there would be a much stronger movement against gay marriage (since Obama opposes it) in FAVOR of civil unions as a "compromise" solution. In reality this ignores the dignity of individuals in favor of stigmatization. With McCain, as well as a Democratic majority congress there is NO chance of a FMA making it through the congress and no chance that the status quo would change on the federal level. On the state level there is still a clear need to fight for the EQUALITY we deserve with McCain. With Obama a lot of people will bow to the "moderate" position of creating a parallel stigmatizing system that is much more difficult to get rid of because "what's the point? It's just semantics"... to straight people at least.
Edit... wow, that's annoying, double post instead of editting what I wanted to say in... still, that helps I think
Amir0x - That's not far off, as counter intuitive as I know it sounds McCain DOES energize the gay rights movement more and that's useful. As for baby steps... there's a difference between baby steps and dead end paths. I view civil unions, presented as Obama does in terms of EQUALITY, rather than as a step along the road to equality as a dead end discussion.