While by most accounts it sounds like a drunk who couldn't control his car, one has to wonder if the McChrystal article didn't give him the kind of profile and bona fides that led some whistleblower to seek him out. IF (and IMHO, that's a big if), this was something nefarious, I would suspect it had more to do with something he was about to publish, rather than something he already had.
His last piece hit the NSA thing pretty hard and named some names (known and unknown) of people harrassed by gov’t.