besides it's clear that filipinos are genetically predisposed to be the best nine ball players and boxers in the world.
i'd say the whole funneling kids at an early age to positions that seem right is a good argument. it's not to say that blacks can't play qb, but they are probably better at many other positions initially and are placed accordingly. as offenses change and the qb position demands different skill sets, i'd imagine you'll see a shift. arguably you already have.
there really isn't any doubt that, by and large, black athletes have a more burst and simply run faster than anyone in the world. the best sprinters are black. you put fast kids at rb, wr, and db. black kids are usually faster than white kids. if yu have two kids who throw equally well, but one can also catch and run faster, the less fast one is going to play qb.
don't know if there is any sort of internalized racism to the decision. maybe. i don't believe anyone who says they aren't 'racist' in terms of forming opinions about other people based on their race or ethnicity before they know the person. my longstanding prejudice against italians hasn't harmed me at all.