While i don't know much about sociopaths, i'm concerned with this distinction between fantasy and reality. Fantasy is not necessarily a vehicle for real action, in fact it is often the opposite. Societies that have introduced access to porn into the public sphere, have been seen to have a lower rate of sexual assaults than countries that have not done so.
What if in some cases virtual violence can actually act as a buffer for real violence?
Besides it seems overly simple to look only at this one factor, as noted, there are probably many things that determine the creation of a sociopath.
If we were to say that fantasy is simply a vehicle for action, we would also have to say that people who fantasize about enjoying rape, will also enjoy actual rape, which seems an utterly grotesque and wrong thing to assume.