They not only assume it's for black people but also for poor people. Affordable housing is just less than market rate but less than market rate may still not be affordable for most people.
For example lets say you have a town with nothing but million dollar homes.
Well affordable housing may mean homes selling for 700 to 800k.
Now who is that affordable to? Certainly not someone making 30k and below.
Yet it may be affordable to the kids of the homeowners in the town and/or people making a decent income but can't afford a home in the million dollar range but want to live in that town.