wrong.
If there were bad guys on the flight, wanna guess who they would pick to be the first victim? Mmhmm...the AM. Take out the resistance first.
Most police and security wear uniforms. Air marshals do not as a bluff because they aren't on most flights. Having a government worker sit all day and mostly do nothing, and give them a loaded gun, is asking for it. Never in the history of aviation has a pilot shot an unarmed passenger in the back as they were running away. An air marshal did.