Tonight derails most of these theories about the so-called "former cop". He's obviously neck deep in whatever is actually going on.
To me this seems a lot like a domestic terrorism plot. Maybe that's who bombed the cities (with suitcase nukes) and they are mounting survivalist groups in all of the rural areas of the country in order to take over.
Non-ex-cop is either one of them, or if we insist on him still seeming like a hero, maybe HE'S the turncoat he's warning the others in the group about (in other words, he's hiding in plain sight by being the one to point the existence of a traitor out to them).
Jericho, due to its geography, seems like it was planned as a logical post-nuke target for occupation by these forces, but non-ex-cop is using the threat of a turncoat to warn the others away. Perhaps he's trying to protect Jericho, or if he's actually working for the government and was some kind of spy planted with the domestic terrorists (under this theory he was unable to warn the government about the attack, but had been planted deep cover by the FBI perhaps to surveil them), perhaps he's just trying to buy time for the Feds to show up, assuming they ever can.
He's also using a computer with long range communication capability and that needs to be explained. EMP would exist even with suitcase bombs and the bulk of our communications infrastructure would be out. Is this think working by satellite perhaps? Radio waves? Certainly its not using land-lines.