Look like the guy just got lucky because the staffs at the Bell Centre had no directive for that kind of stuff.
Whoever try to pull that kind of crap for now on won't be so lucky: "The day after the game the Canadiens said this was the first such incident to ever happen at the Bell Centre, and that in future spectators who bring lasers to a game will be immediately removed."
It's strange but I seem to remember going to the Bell Center (or Molson Center back then) and reading on the jumbotron / hearing a public announcement that it's strickly forbidden to throw anything on the ice and use laser pointers. Therefore, pretty sure they know what to do if they see someone using a pointer.
Obviously I don't think they mind if people throw caps & hats when a hat trick occurs.