I'm trying to imagine reading it if I didn't know who Oshun is but I still think I'd get it that here are some descendants of slaves who got cut off from their original culture trying to reach their Goddess. Fantasy often asks of us that we believe in completely made up gods and goddesses and the cultures that go with them so it's hard for me to relate to this story being rejected just because no one will already know Oshun (and they were wrong about that, weren't they?) Besides, people like Luisah Teish have introduced many of us to African deities.
I think what they were really trying to say when they rejected this excellent story is, "We don't care about the struggle of people of color trying to reclaim their traditions because it's not about US." That kind of ethnocentrism and racism disgusts me.
That said, it's a beautiful and moving story. Judge for yourself. And bravo to Expanded Horizons for having, well, expanded minds. :)