@TSA Administrator David Pekoske: "I don't think any of our officers groped any passengers…
Why would a traveler expect TSA to take their groping complaint seriously when the TSA Administrator has already determined that TSA screeners don't grope passengers. Every employee in the TSA chain of command will be aware of the Administrators position on this matter and they will be very unlikely to rock the boat. The public already knows that TSA lacks integrity in its actions towards travelers forcing the public to seek other means of redress.
The core problem is having the offending agency investigate complaints against themselves. There is a vested interest in not making the agency look bad or doing something where the public loses trust in the process. I think that trust was lost years ago but there are still some who have their heads buried deeply in the sand.