The reason i assumed you were assuming race was below. I can see where you're coming from though.
" the higher the rate of crime in any demographic the more they will be arrested, imprisoned and sometimes shot by the police and this will end up with disproportionate numbers in jail and / or shot dead by police. "
was the quote and you said
" So if blacks are more likely to commit crimes, they are more likely to be in jail, and involved in sometimes fatal interactions with the police? So by that logic if you are black you are more likely to be involved in a crime, or more likely to be shot by police, as it is demographics? "
All thplinth is saying with that is to come to the conclusion that from 13% population to 35% prison population to assume it is because of a racist system requires there to be equal rates of crime. Explaining the axioms built into that statistic cause as you say, they can be spun to say most things.