He's chosen a lame argument, however. His assertion that such matters are state issues, and that what the California state supreme court did is therefore A-OK, confuses -- out of either ignorance or disingenuousness -- two distinct issues: Federalism and separation of powers.
Sure, federalism principles hold that state issues should be decided on the state level (setting aside, for purposes of this discussion, the implications of the "full faith and credit clause" -- the potential impact of which justified the creation of DOMA).
But separation of powers principles require that each branch of government adhere to its own role. As every schoolchild should know, the role of the judiciary is not to make the law; it is to interpret it. Here, judges created new legal rights and obligations that are not clearly appearing in (or at least obviously implied by) a constitution, doing so under the guise of "interpreting the law."
That means the court has engaged in a quintessentially legislative function (i.e., making the law). On top of it, given that this legal right/obligation was not only not recognized by the people of the state, but was recently expressly rejected by them -- and, in fact, runs counter to the understanding of marriage for centuries -- it is an act of unbridled arrogance . . . even lawlessness.
It's tempting for those who see themselves as libertarians to approve this ruling, on the reasoning that the state shouldn't be involved in marriage anyway, or some such rationale. In truth, though, those devoted to the cause of liberty should be the first to protest it -- as should every freedom-loving person, whether or not s/he supports the cause of gay marriage.
That's because, if a largely unaccountable black-robed obligarchy can create legal rights and obligations out of whole cloth against the expressed will of the people, haven't we the people handed them a blank check to rule over us, guided only by their own whim?