They said in the link I posted that they are "progressive" in their politics. That's not shocking. I think that their church members were raising a stink about these so-called marriages, so they had to say something.
Show 'em my motto!
I'm not necessarily advocating homosexual marriage (actually, I really don't care since it doesn't impact my marriage), but the civil rights trademark, rather than morals, could be the motivation behind these preachers rejecting homosexual marriage.