If they are denying access in order to wait for police, then that's an unlawful detention. (It's illegal - a civil violation punishable by fine, not a crime punishable by jail - to leave TSA screening before they finish. So per
Terry and the usual administrative search law like DUI checkpoints, they're only allowed to keep you for as long as it takes to do the thing they're there for, and not a minute more.)
They are allowed to deny access because someone doesn't cooperate with the
security screening. They are allowed to call the cops, but only in the same sense as
anyone is allowed to call the cops. They can't (legally) hold things up on that.
I strongly recommend listening to the
Pellegrino en banc oral argument:
video,
audio. (See also panel argument
audio.)
You may enjoy hearing the judges outright laugh in the face of TSA's lawyer for suggesting that TSA doesn't detain people.
Yes: APA notice and comment. See
EPIC v DHS, 635 F. 3d 1 (D.C. Cir. 2011).
It's a somewhat more subtle question. I believe that they are told not to search for drugs. However, if they see something that they think
might be drugs, I think they do in fact do a follow-up search for that, which violates
Terry. And I know that their internal magazine repeatedly praises TSOs for drug, immigration, and miscellaneous criminal (e.g. outstanding warrant) "catches". And I know that their study of SPOT / "behavior detection" uses those kinds of outcomes as proof of effectiveness.