Obama has been steered to pretend any old thing under the sun whether it was intended or not.
That is a libertarian trait.
Obama used the libertarian/rino arguments and method to avoid the issue.
Obama was against a constitutional amendment or DOMA, calling it a “state” issue, although amending the constitution is completely legitimate and constitutional.
Obama/libertarians/Rand Paul know that they/he are running for federal office, where he would make policy for gay marriage at the federal level, in the military, for federal employment, and in immigration, the resulting pressure and public opinion making it impossible for a few states trying to deny those marriages, and deny marriages from other states.
Libertarians and leftists know what they are doing, and they know the language to use, in the end, they get what they want in social liberalism, and have, for 50 years.