Two or more people who share goals and values, have long-term commitments to one another, and reside usually in the same dwelling place.
I don't see anything having to do with children in that definition, do you?
The title of his "article" is even worse: "Dehumanizing Marriage." He's actually explicitly saying that gay people aren't human. Once again, opposition to gay marriage has nothing to do with the smokescreen of legal or traditional arguments they put forth. It's all about hatred of gay people and using them as a scapegoat in order to drive conservative turnout.