When you play a board game, you usually aren't censored and can tell your friends what you think of the game. I don't see why it should be different here. I, for one, would not play any board game where OOG talk is unacceptable.
If it's a RP game the point is to have IC be the predominant form of communication, immersion and all. A player constantly whining would certainly be quite annoying to the group, and one that stated that the fun of the GM is of absolutely no importance to him, well, would not really fit into the whole idea of friendly game.
