I'll cite precedent!
Mihawk's move list will consist of Void/Darkness/Nothingness attacks because in the games he also has attacks themed this way.
It also points to destructive haki being dark and unifying haki being light.
Blackbeard destroys things and his nature is nothingness related to black Haki while Luffy's is related to white and creationism.
And if you think about it, it makes sense because if you destroy something there should be nothing left of it.