When looked at from a number of conservative standpoints — for individual freedom, reduction of government interference in lives, and, yes, even "thinking of the children," there is a strong argument for allowing same-sex marriage.
Indeed, that only drops away when you bring in religiously conservative arguments.
The author (and the folk he quotes) underplay, perhaps, that there are, in fact, people who would argue strenuously that gay people should not have custody of children, and that their bedroom activities should still be criminal. I suspect, though, that ship has largely sailed, and while those positions are still trumpeted loudly and unabashedly by preachers and punditry who have staked their fame on such things, most ordinary citizens would disagree. In which case, the arguments from the article follow pretty logically.
A conservative case for gay marriage
Do it for the children.
In 100 years the Conservatives will claim that they invented gay marriage. So will the Christian churches
+Rick Gary As long as they are not using it as an excuse to oppress yet another group, I'm okay with that.
+Rick Gary Oh, come on. Next thing, you'll be claiming is that they made-up Christmas and Easter.
+Al Hunt not to mention, American democracy and abolition movement