It literally is theft of government property. Nobody is supposed to have access to those servers and that data without first being vetted and given a security clearance, and guess what Elon doesn’t have? Or any of his minions who are romping around the buildings.
Arrest won’t happen while Trump is in charge and his cronies rule at the Department of Justice. There’s no state to file charges under their own laws, because DC isn’t a state – the only jurisdiction there is federal. But several lawsuits have already been filed, and more will follow.