Going through his "personal effects" is one way to determine is someone is lying. Strip search seems ridiculous unless they felt he was smuggling something.
The process to even "prove" someone's a musician is ridiculous, and on top of that, you as much as need to prove that this "job" couldn't be done by an American. Music is not some commodity that can be provided by just anyone. You want a certain celebrity to headline, you don't just want some guy who happens to sound similar.
Since when is a touring musician stealing jobs? It's a process that's obnoxious and time-consuming even for someone who does it day in, day out. I can't imagine what a headache it must be for a hobby musician just trying to have fun.
Apparently everyone agrees it's OK to search a smuggler. What level of proof should CBP agents need to decide this?
What other potential criminals should be searched? Someone that appears to be intending to reside or work in the US despite not obtaining a visa? Can they search their belongings to help determine their intent? Or should they just close down the visa waiver program entirely and force everyone to clear positively before coming to the US, so that border agents have an easier time?
Really the only plausible thing I find is that for things like strip searching, a supervisor should need to agree that the person poses a smuggling or other threat that a strip search is likely to prevent.
But either way, it's far more complicated than "this behaviour is always unacceptable".
Just a "threat?" How about evidence?