Not being allowed back into this country after you've left is one thing. Being deported when you are legally married to a citizen is quite another, and short of the immigrant committing a felony, I don't think it happens very often, if ever. It seems like the government bends over backwards to help married hetero spouses find a legal way to stay here.
My mother and father had to leave the country and lived in Canada temporarily while they sorted out immigration issues. They were indeed married at the time. Granted this was decades ago...but still. I think your quote is oversimplifying the issue greatly. And I think its oversimplifying it to say something of my parents nature is the same as a married lesbian couple confronted with immigration issues too. The truth is somewhere in the middle but i certainly don't envy the situation of the lesbian couple at all.
As for Obama. IMO, i think if we were strictly talking about him as a person, i suspect he always favored gay rights. But he's a politician. If he came out from the gates full force pro gay rights half a decade ago, that would have definitely hurt his electability IMO..and I"m sure he knew this.
But now he's elected...and its several years later, and the gay rights movement is changing always. This is a great time for a president to come out and stand for gay rights....he played his cards right IMO, and it worked in favor of gay rights always, not against. You can't, as a president say "I stand behind gay rights" if you never get elected as president in the first place. And if it does help to get him re-elected? Still good for gay rights overall.
Politics is a game, whether we like that game or not...it is.