... if you aren't detained you are free to go. And if you are free to go, you are free to stay, unless the property owner has trespassed you. TSA doesn't own the airport, at least in my state. So how can they trespass you from the airport or otherwise continue to detain you from moving forward?
I mean, I know you're right, and I know you will always lose if you try, but I don't understand the legal basis.
Presumably the airport or airline has agreed to (or would agree if asked to) have TSA decide whether you are “free to go that way, towards the airplanes”.
You are already free to go that other way (towards the street), but not necessarily free to go the way you want.
I don't think it's a matter of whether or not you are free to go. It's a matter of whether they let you on the plane.
It's just federal law.
Cities don't own restaurants either but can fine them and close them if health inspections fail, because there's a law for that.
The legal basis is the federal laws written specifically around airport security.
As far as I can tell, a person is free to go if they refuse screening: They won't be getting on a flight, but they can just leave. There's no detainment involved in this process.
Whether they can then elect to stay is a different matter, I think.
But so what? How long would a person have to stand in a screening area before someone who properly represents the ownership of that space shows up and authoritatively tells them to GTFO, do you suppose?
You are free to leave. You aren't free to go wherever you want. You aren't free to go into the employee areas, or out onto the runway. If you don't clear security, you aren't allowed in the secure portion of the airport. Not allowing entry into an area is not "detaining you from moving forward".