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.