I think its all of the above,
Some fear bumping into you later on, at some predominantly black event!
Others think black guys will fuck around,
I also think some fantasize about "Escorting" being some sort of glamorous thing, i.e "Older white guy, suit and tie, 5 star hotel. A brother who's probably from the same sticks as they are, ain't that glamorous.
You might think its some B.S but read the drivel on their profiles, especially the Enterprise Girls and that other girl I think her name is "Bree" lives in Liverpool Street; its not too far from the truth