If he was to go in favor of the state (really the people) you and I both know from experience the sodomites will call him a traitor and subject him to harassment and worse.
(Yes, I know you cannot do that to a federal judge. But, again, we both know the law has never stopped these lunatics before.)
He can't toss on grounds of state unconstitutionality since it is a state amendment, he can't toss it on fed unconstitutionality because the feds have ruled that it is constitutional for the states to ban, or allow, homo marriage. He has no grounds for tossing it. Period.