Sadly the TSA and really any screening process is all about trying to find abnormalities. There is no way around it, using their example if you "look" like a female and are wearing baggy underwear while 99.9% of females do not. That is an abnormality. That alone won't trigger anything, but a combination of things (purely statistics) should require a search of some sort.
I don't think the issue is with that, I think the issue is with how it is handled and what the "search" is.
Nobody ever wants to be singled out, and no one wants to be that 0.01%. But the sad truth is, some people will be, and just based on the amount the 0.01% will be the minority.