Cynically? That sounds like a standard interrogation technique. Keep them off balance, upset them, try and force them to stop lying so as to get the drink they need (not that the OP was lying).

Now for the next question: Is this a suitable way to interrogate someone who is not under arrest and is presumed innocent? Is the false negative rate of TSA checks low enough to start assuming that someone is guilty?

The false negative rate of the TSA is nonzero, ergo it is not low enough to start assuming someone is guilty.

On the other hand, the true positive rate of the TSA is zero. Not one single person detained by the TSA has been charged, much less convicted, on terrorism charges.

When do standard techniques start to move into the territory of enhanced interrogation techniques? 8 hours without water? 12? 18? 48?

>> Of taking the picture?

Zersetzung?

That's my thinking.

If I were only slightly more paranoid than I am, I might suppose that it was intended to be a chastisement for practicing what the officer/agent perceived as a weird, scary, terrorist religion.