You seem to be missing the fact that "incel" isn't predominantly a slur we use for others. People self-described as "incels" first. In a convoluted way, to the incels, being as they are is a badge of honor.
So the central premise of the essay seems misguided, and it's definition of what an "incel" is seems to bear little resemblance to how members of incel communities describe themselves and their views. — Echarmion