That's not true though, that's sort-of the exact opposite of what a self-reference is. Only examples of what you're talking about is in the case of an
indirect self-reference: such as a proposition A which is the negation of ~A, which in turn, would just be A, which makes it so A indirectly makes a reference to itself by the existence of another, in this case ~A. And this clearly only works on paper any way.
As to why in this case self-reference cannot apply to the darkness: because the scan itself says that the darkness is incapable of referring to oneself without the presence of another (as proven by COIE).