Even if the chemical detector did trigger an alarm: These devices are not faultproof, and if you can't find an explosive, can't find surgical scars, can't find

Even if the chemical detector did trigger an alarm: These devices are not faultproof, and if you can't find an explosive, can't find surgical scars, can't find anything in the baggage, you could safely assume the passenger does not have any explosives on or in himself. The only explanation that makes more sense if the TSA, NSA or FBI had warnings about very cleverly implanted explosive devices and want to keep that knowledge hidden. That would explain why the pat-downs didn't convince them (maybe they tried to evoke a pain response), why they didn't give him anything to eat or drink, and why the JetBlue representative didn't want him to fly on this day, but was fine with the next day...