I completely agree with you objectively, SS.
However, when you're talking about providing an intimate service to someone, I think it's up to the provider to make a personal call on what they can handle. If they have PTSD due to a previous traumatic experience with a member of a particular race/age group/whatever, then they may feel unable to offer a good service to others in that group.
I personally have had bad life experiences with a number of white men, one of whom had a strong Swansea accent. For this reason I wouldn't ever tour Swansea, but I don't bother putting on my profile about it, because the chances of someone from there contacting me are slim.
I think most SWs who've had traumatic experiences with white men probably realise that since white men are 50-90-% of the market, they are going to have to either manage their feelings, or leave the business.
It's equally possible that some escorts do refuse white men if they're working somewhere they get enough trade from other ethnicities (it would certainly be possible in London.) But can you imagine if you put "I don't see white men" on your profile - discriminating against a group which objectively has the highest privilege in history would cause an insanely entitled response. Certainly for every time I've turned down a booking because I didn't like the attitude on the phone, the most aggressive and abusive responses have been from white guys (or guys who "sound white" I guess, since I haven't met them.)