Maxperson
Morkus from Orkus
An example you've given is that a player has played through a given adventure before. If that player applies previously learned knowledge to the current gane, it is 9nlu because he's treating the game as a game. Ergo, definition is broad enough to cover this.
You're interpretation is just that, an interpretation. As the words are vague, it's even a good one. But so is Max's. That paragraph on metagaming is vague enough that it supports both of your views.
It's really so overly broad and vague that it's useless.