Seeing that in this timeline, our Wizarding World does not exist, then it would make little sense for the law to be here, much less a Ministry of Magic to govern.
Nevertheless, that doesn't mean we can or should go flaunting our magic, super powers, pokemon, etc for the non-Displaced to see. It was essential enough for the military which was here before to require that of us, and I support it now, despite the official lack of the military's presence.