Using scare tactics like this isn’t effective and it will just further the desire for a police state. Instead of saying “these other bad guys can hurt us”, call out the evil these masked men are doing.
What ifs, especially ones meant to scare people into action will ultimately reinforce the police state.
A vampire police officer would have to abide by both rules. They would need a warrant and an invite. A warrant is legal permission, but not an invite.