An administrative search by law can be NO MORE invasive than necessary to meet its goal. The stated goal of the TSA is to find WEI. Both the Nude-o-Scope and grope-a-citizen are far more invasive than necessary to detect WEI.
Asking how much cash you are carrying has nothing to do with WEI and therefore a TSO requiring you to respond to that question before allowing you to proceed into the gate area has exceeded their authority.
A particular airport security screening search is constitutionally reasonable provided that it “is no more extensive nor intensive than necessary, in the light of current technology, to detect the presence of weapons or explosives [ ] [and] that it is confined in good faith to that purpose.” Davis, 482 F.2d at 913