I think you're flipping cause and effect here.
We can see plenty of examples in the history of the US of people, when left otherwise unencumbered, either ignored the needs of others at best or put their own race first at worst. The idea of segregation isn't being introduced here, existing segregation and related behaviors are being responded to. They aren't saying "this man is unable to perform this role due to his race" in a racist-against-this-person way, they're putting additional structural checks in place as a preventative measure.
So here people are trying to make that structurally more difficult. Which is arguably a more realistic and rational choice than simply saying "things will be fine if we get better people."