I'm quite sure it's blackburn. Here's why:
1) The "Troll" comes back shortly after Blackburn stirs the pot about moderation, trolling, etc.
2) MPA was a jerk, but he stayed away from each forum when he was banned.
3)
Hey super sleuth, 99% of the identities are "non public" (by which I think you mean using one's full name which is not the smartest move on the internet)
MPA was never bothered by net security and even posted a scan of his CCW (or some similar ID) on one of the other boards. Blackburn has always shown himself to be uptight about security.
4) It's in Blackburn's nature to come back periodically and troll.
Chris