A prominent libertarian commentator adds her opinions and makes what IMHO is an excellent point in her blog
here:
The TSA has no business looking for drugs, outstanding arrest warrants, or immigration problems unless it has serious reason to believe that the person involved poses a serious threat to air safety. If it is going to serve as an extension of every other sort of law enforcement, then its searches should be subject to the same requirements for probable cause, which would allow almost everyone to travel without submitting to TSA examination.