I think what he meant by "predatory racism" is the very existence of the check-cashing industry with predatory fees for cashing checks (in this case, 10%, which is actually a low rate for the industry). It used to be payday loans, but when Georgia ruled those illegal, the same companies simply changed their names to some variation of "check cashing" and continued to charge exorbitant fees to teens working through (or instead of) high school and immigrants, most of whom are minorities, who can't get a bank account because of their age and/or immigrant status.
Those workers are paid via check, and since they don't have a bank account to deposit the check into, they often resort to the check cashing robber barons who will do anything they can to take as much money as possible from their "clients". Holding a teen's ID and money order ransom because he "fits a profile" sounds like par for the course when it comes to those morally bankrupt businesses.
As for the race of everyone involved in this particular case, I take it you've never been to Atlanta. I live there, and I can say first hand that even black cops in the city will profile black youth.