Benignuman: I’m sorry, but that’s incorrect. First of all, the phrase “rational basis” doesn’t appear in the opinion.
Second, homosexuals have in fact been recognized as a protected group, in the sense that legislation against them invites strict scrutiny. In Romer v. Evans, the Court overturned a state law on equal protection grounds because it sought to disadvantage a politically unpopular group (homosexuals). 517 U.S. 620, 624, 634 (1996). The same occurred in Windsor.
Lawrence v. Texas was different — that was decided on due process grounds. If I remember correctly, equal protection was not an issue, because sodomy was illegal regardless of the sexual orientation of the people doing it. The case didn’t exactly proclaim a “fundamental right” to sodomy, but it did declare that the government can’t make it illegal for consenting adults behind closed doors to commit sodomy.
Windsor applied some form of heightened scrutiny (without explaining itself very well) to overturn DOMA on equal protection grounds. (See Alito’s dissent for a better explanation). It is an equal protection case, like Romer.
It’s a confusing opinion, as Scalia’s dissent points out. But it doesn’t establish a general rule that laws expressing moral disapproval are invalid. It is an equal protection opinion, with a “whiff” of federalism concerns, that strikes down a federal statute because it based on a animus toward a group and desire to disadvantage that group, the same group the state sought to protect.