Nah, dude. This is a stretch. Who gets pulled over for 5 under? Racial profiling or not, why does someone get pulled over for driving 5 under the speed limit? Then the cop condescendingly gives him the 3rd degree and snipes back about the guy not wanting casual conversation when he gets agitated about getting grilled after being pulled over for 5mph under the speed limit, which is not a crime. Doesn't matter if you think it might look suspicious. He didn't get him for a taillight burned out, or my favorite "it looked like you weren't wearing your seatbelt". He pulled him over for something that was legal. Period.
Then fight it in court, not on the side of the road. That's how people get hurt (or killed) needlessly. Don't do it.