They had me excluded interviewed, to the point of missing a flight, because they found a phillips screwdriver bit (no screw driver) in my back back. Even reminding them that airlines exclusively do not use these screws in anything inside the cabin of importance, had no effect. I totally agree with your “comically incompetent” phrasing.
You have to declare it to fly like that in the US, though. So either she did and TSA didn’t care, it she didn’t and they blundered.