I'm not well versed in game theory either, but I think that it definitely still holds when you apply it to a game that needs negotiations.
In Diplomacy, I especially start wishing I knew game theory, when it comes to those tactical gambles, in which you have several choices, but your opponent has an equal chance of countering any one of those choices, which one do you pick?
1. You capture a SC, this is your best case scenario, but if you go for it, and your opponent thinks you'll go for the best case, they'll counter this move. So perhaps it is in your best interest to go with the second best move?
2. You move your units into a very nice position to set yourself for the following year. This is a decent choice, and a good one if you think your opponent thinks you'll take the first choice, but what if they use your same logic, and decide that you'll take the second choice, because it seems safer, well then shouldn't you take the first?
These sorts of dilemmas are haunting...