[W]hen the constitutional arguments for judicial intervention are ambiguous, uncertain, and intensely contested, judges should defer to the political branches.Rosen is talking about male supremacy because the primary constitutional argument for recognizing a right to same-sex marriage is that to ban it classifies individuals by whether they are male or female. Obviously, the bans involve heterosexual supremacy. But, here, Rosen asserts that classification by sexual orientation is not entitled to heightened judicial scrutiny. That's a point of legal doctrine, but why is it correct? As far as I can tell, Rosen thinks it's correct because he already believes that this is a matter best left to political decisionmaking.
In my view, gay marriage, like abortion, is one of those areas. The Supreme Court was right to strike down bans on interracial marriage in 1967 because the only plausible social meaning of those bans was to degrade black people and to promote white supremacy. By contrast, the arguments on behalf of gay marriage are less clear. Although bans on gay marriage are (literally) a kind of sex discrimination, it's not intuitively obvious to most people that the bans should be viewed as an effort to promote male supremacy.
Then the question is how to win majority support:
[A]s the social conservatism of blacks and Hispanic voters suggests, it wasn't enough for California voters to see the reality of gay couples in meaningful marriages. This suggests the challenge, in the short term, is greater that many gay marriage supporters hoped. At a Yale Law School conference on the future of reproductive rights in October, Pam Karlan of Stanford predicted optimistically that the gay rights movement was doing better than the pro-choice movement because "gays have come out of the closet" while "women who've had abortions have gone back in the closet." The third of American women who have had abortions, she suggested, should consider discussing their experiences for the good of the movement as a whole.How did that follow? Women have their abortion rights. Why should they act more like people who don't have recognized rights? There is concern that abortion rights could be lost, so there is a continuing political issue and potential for a new all-out political battle.
But the question was what more could gay people do to win favor in the political arena? Rosen doesn't really have an answer. He concedes that many people have strong moral views that are not going to change and asserts "the future of gay marriage will be determined not by judicial activism but by demography." But why? Because he thinks it should?
Why should a minority group that perceives itself as oppressed accept the will of the majority? Why should the intransigency of the political majority convince them that they should refrain from using the courts?