Contrarian perspective: He fits a certain profile. Triggered a bunch of attributes (address move, chemicals on him, etc.). The 9/11 attackers walked through the scanners with knifes. The Boston bombers were flagged, but still traveled freely. After both attacks people were laughing at the stupidity of the enforcement agencies, uselessness of the TSA, etc. Here, the process worked. His account is subjective, everyone…
I agree with the other parts of your post. Here though I think he wasn't assertive enough. No need to get snarky but a request for a cup of water is not something you just let the cop/whoever shake off with a wink.
>> "You also said a lot of things, kid," he said with a wink.
You say "yes, like that I want something to drink, repeatedly." Another thing is to always ask people for their official identification, a badge, a name, a number... They're not supposed to be anonymous.