But seriously, I guess, a socially unacceptable behavior isn't necessarily one that comes out of the (psychological) shadow. The shadow doesn't represent social undesirability; it represents, in essence, what one would think of as 'not me.' It deals with what the individual, not necessarily society, would find undesirable.
So the crux of the whole shebang is the idea that trolling comes from the shadow. That statement needs some more meat to it, because it can't be taken for granted.