Whether you get an answer is dependent on the criteria you choose, but these criteria must have arbitrariness in them even for rational people. Consider the solution concept "never play a weakly dominated strategy." This is neither right nor wrong but an arbitrary criteria that reflects human values.
Saying "the game theory solution is A,Y" is closer to "this picture is pretty" than "the electron will..."
Also, assuming someone is rational and wants to maximize his payoff isn't enough to fully specify him, and consequently you need to bring in human values to figure out how this person will behave.
You seem to be talking about forecasting human behavior and giving advice to humans about how to behave.
That, of course, depends on human values. But that is related to game theory in the same way engineering is related to mathematics. If you are building a bridge you need to know the properties of materials you're building it out of. Doesn't change the equations, though.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.