Gretzky said he was going to spend that time with his family.
At CBC, Elliotte Friedman says that it is likely that Mark Messier and Glen Sather will try to persuade Gretzky to play for the Rangers in the game.
Maybe he has already agreed to play but they are keeping it a secret for a little while. I just don't get why he wouldn't play. He gets to play with a bunch of old teammates, put on the Rangers jersey again, and try to beat the Flyers. Sounds like a winning proposition to me.