Still doesn't make the slash any less of a slash. It SHOULD have been called and it wasn't. He was stupid for the play he made of course, but it doesn't make the slash go away.
The thing that pisses me off most about hockey this year (and many others) is that they'll call everything for 2 periods, then put the whistles away for the 3rd and whatever o/t there is. Call the game the way it's supposed to be called. That was a slash to the wrist which could quite easily have broken his hand. That's a penalty no matter what you say. Look it up in the rule book. It doesn't say "...unless it's overtime of a playoff game" after every rule does it?
Of course there's the chance that the refs just missed the call. THIS should be the case where you tell a player to keep playing. Refs sometimes miss calls, so you should always keep playing until you hear the whistle. By saying that there is a different standard between the first two periods of a game and the end of the game you just encourage dives, embellishment, and Kovalev-ness in the early part of the game, and gratuituous clutching/grabbing, slashing, roughing, etc in the later part of the game.
I would rather have the refs call all of the penalties as stated in the rule book ALL THE TIME, regarless of who it is, or at what point in what game. Sure, there will be a glut of powerplays to begin with until players learn, but that's not the ref's fault if someone slashes a guy's hands. Just don't slash and you won't have any problems. I'd rather watch skilled players skate than goons grab and hook.