I'm not buying that "playing both sides of the fence" would refer to someone who is cooperating with the FBI. If someone was a rat, Silvio would have called them a "rat". I'm willing to bet it's Carmine he's talking about. I watched the scene with Tony at Phil's house over again, and I'm convinced Carmine set Tony up to be whacked. For whatever the reason, Phil backed out.
I'm not sure Carmine and Phil would have Tony killed, doesn't commission have to approve a hit on a boss? If so, Carmine and Phil don't have the authority to kill Tony.
