Looking at guerilla mail, there is no way to contact them and no information about who runs the service. It's a shady company with no legal information as far as anyone can tell. (nothing in the about us or the terms or service pages).
If the police wanted to investigate some users/mails, they would have to get a warrant to OVH to figure out who to contact in the first place (who runs that thing?). It's a fair guess that OVH receiving anything of that sort would shutdown the account immediately.
It's also possible that the police would purposefully shutdown the service and/or seize the servers but rather unlikely. Either way, all the roads lead to the site being dead.