Here is how the NHL rules outline the Instigator Rule:
"46.12 Instigator in Final Five Minutes of Regulation Time (or Anytime in Overtime)- A player who is deemed to be the instigator of an altercation in the final five (5) minutes of regulation time or at any time in overtime shall be assessed an instigator minor penalty, a major penalty for fighting, and a game misconduct penalty, subject to thye conditions outlined in 46.22"
If Colin Campbell is going to stick to the letter of the law with regard to Raffi Torres' hit on Brent Seabrook, then Kevin Bieksa shouldn't be on the ice for Game Five. It doesn't get much more obvious than this one.
Look at the clock. It reads 3:40 when the punches start flying. By any second grade education's standards, 3:40 is less than 5:00 on a clock.
Watch Bieksa pursue Stalberg after a clean, unpenalized hit by Stalberg. Note that John Scott and Torres had already been excused from the game, so Bieksa could feel free to take swings at Hawks players at this point.
Who throws the first punch, or "instigates" the fight? It's Bieksa.