“It’s not contradicted because that difference could be fully explained by issue #1–the rate at which police are stopping different groups. If group A commits X times as many crimes as group B, I would certainly hope that the police are stopping group A more often than group B by a factor of X.”
Now who’s guilty of “mental gymnastics” ? 
BTW, there are experts who disagree with you, and find the death certificate study DOES contradict Fryer. Like I said, this is all interpretive, subjective and highly flawed. Certainly wouldn’t hold up in a science lab! So I’ll stick with what I’ve seen with my own eyes, and heard from those who live the reality.