Closet Tolerant
By A couple of Matt’s commenters beat me to it, but I don’t think it’s really accurate to say that Thompson is taking a stand on “federalist” grounds. He’s never met a federal abortion regulation he doesn’t like, for example, so as with 99% of the population “federalism” matters to him at most in the familiar question-begging sense in which “federalism” isn’t doing any real work but is just a way of concealing your substantive position on the merits. Rather, I think that he’s using “federalism” as a smokescreen for the fact that he’s a closet tolerant who doesn’t really have a problem with gay marriage. Which admittedly I think is even more charitable towards Thompson, and he does deserve of a modicum of credit for not going along with all of the symbolic gay-baiting the GOP base seems to demand.