Why do a pat down if the person is only wearing a bra and panties?

And what if the person would not have worn any bra and/or panties?

What would then the result be?

Arrest for indicent exposure?

And why would a male come into a room when a woman has been ordered to stirip to her undies?

I thought male's were not allowed to be a part of a female search.
To me he was since he didnt know if she was dressed or not.

Unless they have hidden cameras in there.