So, I'll restate my question - how is an intrusive interrogation any less a violation of someone's 4A (and perhaps 5A) rights, than is an aggressive pat down or electronic screener a violation of someone's constitutional rights?
Personally, I don't think it is, but I certainly here a chorus of voices who are advocating that we "defund the TSA and start doing it just like the Israelis". Seems to me that the Israeli method isn't any less constitutionally questionable, at all.
I'm make my point more directly than I did in my original post. The people who say that, haven't a clue what they're talking about.
The answer is yes. It is based on the legal concept of "Implied Consent". Traveling by air is a voluntary act, and is using a federally regulated environment (the air traffic system). Purchasing a ticket implies consent to be searched. Entering a court house or other federal building implies consent to be searched.
Based on your questions regarding the 4th and 5th amendment, one could say emptying pockets, x-raying carry-on luggage, and requiring one to go through a metal detector does in fact violate the 4th and 5th amendment. But court decisions have supported Implied Consent as justifying these searches.
The government already requires certain information be obtained of passengers domestic travel plans, first by asking questions such as "Did you pack your own bags" and by searching checked and carried-on luggage.
This 2005 article from USA Today mentions some of the TSA's training in questioning and observation techniques, and how the ICE side of Homeland Security has been using the techniques for years: Airport security uses talk as tactic.
This 2008 article from The Atlantic mentions the TSA's use of observation techniques and identifying micro-expressions: The Things He Carried.
The idea of questions about the nature of travel are not because traveling to see grandma inherently poses less risk than traveling on business to Chicago. It is all about observing the individual during the question and the response. On the subject of questions, it would make more sense for an observation trained TSA agent to ask the "did you pack your own bags" questions than the airline.
It would also make tremendous sense to ask more questions of those selected for Secondary Security Screening Selection. The idea of not questioning the person who bought a one-way ticket with cash the same day of flight on the nature of their travel is foolish.
All of this makes more sense than putting every 10th person through the naked scanner, or groping grandma because her artificial hip set off the metal detector.
Profiling works, questioning works, and observation works. But there are experts who say naked scanners would not have caught Umar Farouk Abdulmutallab's underwear bomb.