With RC's (putative) reappearance on the scene, I think we need an alternative handle for the guy. "RC" is just going to get confused with RealClimate. "The hacker" or "the leaker" assumes we know more than we do.
Can we think of some snappy alternative along the lines of Watergate's "Deep Throat"? Deep Climate is already taken, of course, but I would have thought we could come up with something else. Perhaps still with the initials "RC"?