I think it is a fair question.

TSA screeners are not law enforcement so I don't know if any legal standards that would allow a search are present. I certainly don't think the Constitution goes away just because a person enters airport property, especially when there is no reason to think the person is trying to access any secure area. I believe Stop and Frisk has pretty much ended on Constitutional grounds so where exactly does TSA derive any more authority outside the entrance to the sterile area than what police have?

I can understand a need for increased security inside the aircraft operating areas of an airport but outside of those areas standard law enforcement standards should apply.