It's edicts like this that are gonna have to be defied with the support of states, if the rogue judiciary and/or bureaucracies are ever going to have their assumed authority challenged.
The governor is in charge of the top law enforcement officer in the state. Tell the people to go ahead and deny the homosexuals marriage on their property, and then tell the judiciary that if they have a problem, take it up with the governor's office. If it goes to the federal court, tell them that the edict is not recognized as lawful.
But I seriously doubt whether Chris Christie will expend political capital of that nature on a social-con cause like this.