I don't see how. If he opposes gay marriage with both his opinions and his vote, perhaps he wants to ask about it so that a support of the same doesn't get on the Supreme bench.
How?
Because DOMA isn't SCOTUS proof, and Dems know that, so they can say they are against same-sex "marriage" all they want, vote for DOMA, and then let the same-sex "marriage" issue eventually go before the presently liberal-leaning SCOTUS and have traditional marriage butchered there.
That is why the Democrats voted against a Cons. Amend. banning same-sex "marriage". It IS SCOTUS proof.