Whatever the rights and wrongs he should know what US airport security is like. They go out of their way to not use common sense as i was told 'they have strict rules that allows them to do their job with clarity'. If you have been selected to get off that is it you are getting off like it or not. Sometimes it is better to know when a battle is lost and work from that.
It is not right but anyone who has dealt with US airports, homeland security etc knows what i mean, these guys are robots, you have more chance of a reasoned discussion with the terminator.
When i go i even act the fool a bit when dealing with homeland security and stuff, like leaving my finger on the scanner until they say take it off and i'll say 'oh sorry' kinda thing. The last thing you want is to bring any attention to yourself whatsoever. I find and acting super kind with a hint of needing their help normally gets you through with no hassle. Maybe a comment to HS at the end of them checking me out that gives them a tiny jolt of pride like 'now i am going to eat all your bbq in every state, been looking forward to this for ages'.