I worried the reference might be too obscure, especially for non-US readers.

Commenting as a non-USian: I admit that it would have escaped me, had I not read about the Nation of Islam in a (fairly terrible) novel. I can't even remember if Malcolm X et al were covered in our history classes, only briefly perhaps. Apart from a few catchphrases or iconic images, there just isn't much awareness. That being said, I still vastly prefer subtle jokes like this to the metaphorical anvil getting dropped on me. *g*