Apparently, George Onorato thinks he has an explanation and an excuse.
'Traditional marriage' is a contract between one man and another man.
The Dan Savage youTube on marriage is exceptionally good at putting a finger on the issue. When Dan says something like (paraphrase), "Straight people have redefined marriage - past tense, redefined - to the point at which it no longer makes sense to exclude gay couples", it's very accurate, even if that is a very complex point to get across in an ad campaign, say
Realizing this can elucidate how some people are talking past each other.
Most of us are looking at a public institution that is 'redefined' and hardly adhering to a single ideal (or any ideal, for that matter) as our fact-set to make a conclusion about what is just, while the dress-up groups, like NOM, are imagining institutions on an ideal plane, "marriage as it ought to be", "traditional marriage", marriage as it is preached, rather than how it is practiced.
One of the things bigoted about their position is that, having failed to stop the de facto 're-definition' of marriage for nongays from its "ideal", they focus millions of dollars on a minortiy, gays and lesbians, to bully and deny. Screw that.
The ethics of that just doesn't work for me, even having heard their arguments. In the past seven years, I'd bet that New Jersey passed out warrants for more deadbeat parents that all the committed gay and lesbian couples who would get married in the first year of legalized SSM. It's things like that that just make it plain they are posturing about 'gay lifestyle', not much more.
In other words, in a comparison of the 'greater evils' of marriage 'failure', marriage for committed gay and lesbian couples just doesn't rank. Opponents don't see it that way, because their gaze seems stuck on the ethereal plane.
(With some stuff, I've been trying to get the ethereal plane to come in line, too, so to speak, but persuasion is not easy, there).
[Good for discussion forums, except it has a "fuck this" in it, that will 'shock' some.]