> Perhaps he believes that the state should remove all recognition of marriage...

Just a heads-up, this is a strawman developed by anti-same-sex-marriage proponents to provide a possible (though not plausible) reason other than denying people their rights why someone might oppose same-sex marriage (and you also have to buy that someone who wanted to grant same-sex couples those legal right would vote/donate/campaign/etc to deny them).

If you're going to assert it, you need to have specific evidence that the individual in question actually believes that.