“Does the TSA have arrest powers or are they just faking it?”
They are faking it. However they can generate charges for the local police to arrest you on.
So rest easy that the security guard reject can screw up your life without justification and doesn’t even have the minimum controls that the police have.
There are airport police departments at each airport. They are usually behind the screeners. Actually, you might not believe this but they pick up lots of people who have outstanding warrants who come to get passengers at the airport terminals.
So, TSA comes to get you with airport police and then they book you with a municipal warrant.
Sad, but I’ve BTDT, but I beat TSA as the screener was trying for a raise/promotion and luckily I had a history of a security pass for all but runway and taxiways. BUT, it was a terrible 3 hours knowing if they didn’t void it I’d be searched everytime I boarded a plane anywhere.
That’s only if you stick around for the abuse....