FWIW, you don't have the right under TSA policy to an *opposite* sex screener. (As you know, everybody is straight, so there's no reason why someone would feel that a same sex screener touching their genitals would be sexually inappropriate.)
If you think you've been assaulted though, you should definitely file formal complaint, as well as tell ACLU, EPIC, your congresscritters, etc. All the contact info you need is in my flyer:
http://bit.ly/tsarights