I'm guessing that Smith didn't get it for leaving the bench. He got it for getting into a fight after the game. Looks like he got 2 for that, and 2 for having 2 fights?
The other players that got suspended (Moore, Roberts and Velliaris) also got involved in fights after the game. Moore was on the ice when the game ended, so it's the only reason that he would be suspended. All of this supports my theory (I think lol).
As heavy handed as the league is nowadays I expected more.
Also, I've heard people calling this a "bench brawl". I think that they either have never seen or forgotten what a true bench brawl looks like.