Clients get to pick and chose who they want to try and book based on their criteria. She's too fat, she's too skinny, she's too old, she's missing a tooth, etc...
SP's are afford that same opportunity, based on their preference also, regardless of the reasons. Race happens to sometimes be one of those criteria, along with many others like distance, hotel ratings, duration length, deposits, etc.
It's better to list these restrictions up front, rather than have clients be disappointed at a later date.