The scumbag did not "resign" in accordance with some contractural procdure. He bugged out in the face of a crisis in which the lives and property of the citizens he'd taken an oath to protect were endangered. That's at the very least dereliction of duty, for which he should be fired "for cause" and barred from public employment and receipt of any form of government (federal, state, local) assistance. Whether it's criminal, equivalent to desertion in the face of the enemy under the UCMJ, is debatable and a question of the strange law of Louisiana. He should be publicly stripped of his badge and sidearm.
Any emergency responder who "resigns" during an emergency, for whatever reason, should be criminally prosecuted.