Couple small hiccup's here though,aren't there? First, this sounds like a closed loop system, so outside of it being a neat little club, no PR value to it as an outreach tool, right? They would still need access to the open grid to disseminate their propaganda and incur the routine risks it presents. And second, all it would take is just one infiltrator to plant a nasty virus and the whole thing goes kaboom, right?
I would favor encryption in the electronic frontier as well as low-tech techniques like one-day codes and other such simple but effective methods ala the OSS days over relying too heavily upon technology.