It is the policy people who are responsible.
Maybe the front line schmoes are abusing the system. The few times I've seen it, the screeners seemed far too over-worked and burned out to be perving. Also too overworked and burned out to be an inconvenience to the bad guys. But I don't fly much, and when I do I'm usually not paying a whole lot of attention to who the screeners are picking.
I really have a problem with being rude to front-line people who are acting in a professional manner within the policies they played no part in setting. Increases the unpleasantness in the world without a chance at solving the problem. If we hassle the screener enough, the screener may quit, but that means nothing to the policy people, they'll just hire more.
The underwear with the text of the 4th is OK with me. Expresses the objection without being obnoxious. The ones that accuse the screener of being a pervert are the ones I don't like.