When Timmy was able to read minds in the episode "Mind Over Magic", he read the bouncers mind who revealed that the popular kids were ten year olds and that he worked for them because he never finished college.
It's unknown if he will return in a future episode. He either quit, was fired, or left to go finish college. Recent Seasons have replaced The Bouncer with regular security guards when Trixie requests somebody to get rid of Timmy for her.
He keeps mentioning the chart in his first appearance.
It is interesting that he's allowed to assault children as in real life, because in real life, any adult that would do such a thing would be arrested for child endangerment.