From a reader:

I found Ross’ arguments somewhat compelling, but I’m still not sure where I am on gay marriage.
Greenwald, on the other hand, was a bit myopic. The question isn’t whether the government would prohibit a particular behavior — gay romance, sex, cohabitation, or even gay people calling themselves married. The question is whether the government would confer a particular status — state-recognized marriage — on gay couples. You can call yourself a charitable organization if you want, but the government will only grant you 501(c)(3) status on you if meet certain standards. The requirements for businesses that sell to the federal government are different than the baseline legal requirements for operating a business. The fact that PBS only funds certain kind of programming is not tantamount to the to the government prohibiting other kinds of programming.
Douthat’s argument (which, again, I only partially buy) is that the state should only confer this recognized status on couples that meet a standard that he says aspires to a certain historical ideal.
It reminds a little bit of the old arguments about the National Endowment for the Arts; some used to argue that the government restricting the sort of art that ought to be funded constituted censorship. It doesn’t. However, a lot of us argued back then that maybe the government ought to get out of the business of deciding what constituted quality art (and, in the PBS example, quality programming.) Bringing that argument over to the marriage issue, maybe the government should get out of the marriage recognition business (as Doug Kmiec (whom it pains me to cite) has argued). Anyway, I think Douthat makes his case well; but I’m not sure I agree with him. Greenwald sets up a straw man of government prohibiting a particular behavior, and then knocks it down.