It depends on how long ago that they made that poor decision. It also depends on if the victim holds a grudge or not, once is likely. So honestly it depends. But, in some States and/or Countries, Schools and Work forbidden Cyberbullying. So in that case, they may or may not accept the fate that the bully has threatened.
Although this may be confusing to take in, I’d say that yes, they should be held accountable, until they learn the fate they have crossed online.