You kidding right, that's just offensive...toward Africans. Americans blacks ain't the same ethnicty as Africans, Africans is a multitude of different ethnic and cultural groups, while American Blacks is a European "descendent" (cultural) Creole culture made up of people with significant ethnic white heritage. This is just a White Man burden just in a Blackface-costume instead of the usual tropical clothing.
Valdemar II
More to the point the story has American blacks [i.e. negroes] coming to rule and identify with a predominantly Arabic region, where they have traditionally viewed as 2nd class citizens if that.
I think that's a more serious flaw in the story than suggesting that ideas from the west are in some way fundamentally alien to people from other lands.
Steve