I'm pretty sure Christie has no power to stop a referendum for gay marriage. He basically wants to punt and take himself out of the equation, not unlike with the senate special, and say it's not up to me. It's the safest political move given how hard it is to please either national Republicans or New Jerseyans without alienating the other. But I disagree with this article calling him consistent exactly. On DOMA, he says the judgment of the democratically elected executive and legislature should be trusted on the issue of marriage. On NJ, he says the opposite. The only real consistency for Christie is doing whatever seems to carry the least risk for a presidential campaign. As with Obama before he "evolved", I find it pretty hard to believe Christie privately opposes gay marriage in the way Santorum or even Romney did.
What he's saying is he's against gay marriage, but if it becomes out of his hands, then there's nothing he can do. I suspect he's like me and doesn't have a strong stance on the issue one way or the other.