> If you set off a gas chromatograph for nitroglycerine and then say you have heart tablets then you'll be fine. He obviously set off a specific trigger AND couldn't account for it (although they clearly tried to get him to).

That isn't what that line of interrogation was for. The TSA goons probably don't know anything about chemistry or how their machine works, they were simply trying to rattle him and get him to say something incriminating.

Specifically: when somebody says, several different ways, "why are you setting off my explosive detector?" what you do not want to say is "I don't know! I don't have any explosives!" Because it will elicit a response indicating that nobody was accusing you have of having explosives, why are you being so defensive, etc. etc.

Too bad they couldn't even tell him what set it off, since he clearly did not remember:

  "I can’t think of anything. What does it say is triggering the alarm?" I asked.

  "I’m not going to tell you! It’s right here on my sheet, but I don’t have to tell you what it is!" he exclaimed, pointing at his clipboard.

''EDIT: formatting''

Not letting him drink water or whatever is simply inhumane. Not giving him information is simply a judgment call or policy decision. Perhaps it is against policy to reveal which exact molecules their machines react to.

So what you're saying is all I have to do is carry heart tablets and then I can pass nitroglycerine through security? Don't get me wrong, I'm sure it's more complicated than that. But I can't help but feel that if someone really wanted explosives to get onto a plane then they wouldn't try walking it through passenger security. Or maybe they'd just say the magic words that indicate a false positive and walk straight through.