In the same post cited below, Greenwald continues:
"Courts don't rule on moral, theological or spiritual questions. Such matters are the exclusive province of religious institutions, philosophers, communities, parents and individuals' consciences, but not of the State."
But look a couple of paragraphs later:
"The court did evaluate the question of whether there is convincing evidence demonstrating tangible, empirical benefits to recognizing only heterosexual relationships, and found -- as have the overwhelming bulk of social scientists -- that no such evidence exists. That's why it's unconstitutional to continue to exclude same-sex couples from the legal institution of marriage: because none of the empirical or utilitarian justifications legitimately considered by the State can support that exclusion."
So, Greenwald is not at all against the State legislating morality... as long as it's utilitarian morality it is legislating. I suspect that he doesn't even recognize this as advocacy of a special, controversial sort of morality that alone will determine government actions -- the ideological dominance of the utilitarians has gone on for so long that Greenwald just sees it as the way things are that the State is a utilitarian calculating device. Greenwald is not for keeping religion out of the public sphere: He is for banning every religion but his, which is utilitarian liberalism, from the public sphere.
PS -- I had hoped to marry a Millian Error one day.