One of the weird strains of chattel slavery apologia/eugenics apologia is the claim that black athletes are the result of selective breeding programs by slavers. As if a few generations of inbred aristocrats with no plan or understanding of genetics mostly not bothering to even attempt a selective breeding program and never doing so with any coordination would have any impact at all relative to other environmental stressors.
It’s a mix of trying to validate eugenics nonsense, attempt to whitewash chattel slavery, and push race science nonsense.