A reasonable politics of “family values” needs to contain some penalties for heterosexuals with anti-family behavior (see, e.g., Dick Vitter, Rudy Giuliani) and support for gays with pro-family behavior. What they have right now is just loathing of gay people masquerading as defense of the traditional family.
This is true, but there’s another angle to it as well. Republican social conservatism, at least as instantiated as state policy, is about imposing burdens on other people to make oneself feel virtuous. Bans on abortion don’t seriously obstruct the ability of the affluent women Republicans represent to obtain safe abortions. Large homes in the suburbs are very unlikely to be subject to no-knock searches. And so on. These policies are basically a free pass for the Republican elites who advocate them, appoint judges who uphold them, etc.
And this is why gay-baiting is such a useful Republican tactic, even for the many closet tolerants among GOP elites. To put it mildly, it’s not obvious why gay marriage is a greater threat to family stability and “traditional values” than, say, no-fault divorce. But there’s not going to be a constitutional amendment to ban no-fault divorce introduced in Congress or serious attempts to get rid of it in most states — somehow, social conservatism always loses most of its appeal when restrictions on your liberties and privileges, rather than those of a stigmatized minority, are involved.