"You tell your kids not to go to Chicago because of the crime, I tell mine not to go because of the police." --> "Politically Correct" racism, just as bigoted as some redneck telling his kids not to go to an integrated school because of the black kids.
Yeah, because the only way any black kid in Chicago has ever come to an untimely end was because those evil racist cops gunned him down for no reason. /Liberal self-reinforcing prejudice.
You obviously don't like your child very much if you want to convince him to mouth off to police instead of respecting them like anyone else should. If you really think the police are doing something wrong, the appropriate place to deal with it is in a courtroom, not some racial-war street fight that you are guaranteed to lose. You might find that if you drop your race-war attitude towards the police and treat them like human beings, they might just not be as "racist" as you think they are.