I'm not saying Airbnb discrimination is illegal, I'm saying that anti-racist restrictions on landlords are reasonable in principle, and therefore Airbnb should

I'm not saying Airbnb discrimination is illegal, I'm saying that anti-racist restrictions on landlords are reasonable in principle, and therefore Airbnb should apply them. As for the law, while you note some exceptions to the federal housing laws, states may supplement. For example it is illegal to discriminate in California even if you're renting a small home.