So if they decided that an occupant's epidermal melanin content was an "aesthetic standard" would that be OK?
I'm sure the HOA is specific enough about the standards being with regard to the property and house, rather than the race of the occupants. The sad fact of HOA agreements is that you voluntarily cede some or all of your property rights to the HOA, from the color you're allowed to paint it, to the shingles you can put on the roof, to the structures you can erect in the yard, to everything else. My cousin isn't even allowed to mow her own lawn -- they're required by the contract to hire it done. That's why I won't live in one.