It is as it seems a tacit refusal to engage -- at least in the main political arena -- on the politics of the issue. This is compared to 15+ years ago when the Defense of Marriage Act fell like a dirty bomb in the middle of national political dialog and a Democratic president and (let's not forget) the vast majority of national Democrats scrambled to get behind it.
This is probably the best example that the fight over gay marriage is all but over for those who have eyes to see it. Accusing you of a 'playing politics' is pretty much always a sign that they're conceding the politics are good or at least good for significant parts of your coalition.
But there's another part of this that merits mention. I think this is actually a smart and somewhat subtle approach from national Republicans. I think these folks realize that going all out culture war on President Obama on this is not a good idea. It will have bad knock on effects in future elections. But even more important, too strong a push would confirm the idea a lot of people got during the primaries that the GOP is a narrow and exclusionary party, holding on to viewpoints that are clearly receding into the past.
That can be damaging politically even among voters who -- all things being equal -- would just as soon not have two men (or two women) be able to marry each other. In other words, there's a real trap Republicans and Romney can fall into here.
As long as they can play it cool in the mainstream political dialog (opposing without demonizing) they can assume (correctly) that the folks who passionately oppose gay marriage don't need harsh statements to get riled up.
As a political approach it makes a lot of sense to me. The question is whether core Republican voters will be satisfied with such a low key response from Republican leaders.