Although some misguided courts might have upheld the introduction of this illegally found evidence, the fact remains - until the police actually show up, the TSA has no legal right to physically restrain or detain a passenger, and any attempt to hold, restrain, cuff, tackle, threaten or otherwise prevent someone from leaving the checkpoint until the police arrive is illegal and a crime.

If the police are standing right there, then the issue is moot - but if they need to be called, and there could be a 3, 4, 5 minute or longer wait for them to arrive, then the passenger can gather their belongings and leave and there is nothing legal the TSA staff can do to stop it.