the constitutionality of gay marriage is slim at best.

Uh, no, it's entirely solid, and in fact has already been decided. Perhaps you (and Rand, for that matter) should read your 14th amendment.

And it's far more realistic for a mutual decision in Congress than simply permitting gay marriage as a whole

Gay marriage is permitted as a whole. This was permitted in 1868 with the passing of the 14th amendment, which the Supreme Court finally caught up with last year. You should read that amendment. I'm pretty sure that something which has been around for 150 years is fairly realistic.

It's not unrealistic-- it's the most realistic way of legislatively establishing gay rights that currently exists.

Well, look, I know you're a libertarian and you live in a fantasy world so this seems realistic to you, but for those of us in reality, no, it's not. Eliminating all governmental mention of marriage is not realistic. Everyone knows this. Including Rand himself, I hope.

These are just ways for Rand to dogwhistle and weasel his way out of actually supporting gay rights. If he were a libertarian, if he actually cared about liberty, he would come out and say it straight up that he supports equal treatment of everyone, and everyone's freedom to marry who they like. He has not. He weasels and retreats. He talks about "traditional marriage" as if it's a thing. He supports the right of the state to discriminate and to take away people's freedom to marry who they like, under the guise of "states rights," which is absurd, as if it's more valid for a government of 38 million people to take away freedom than it is for a government of 318 million.

He is a hypocrite, and he does not stand for freedom.