Seems ironic to ask this on a post where a guy's cheating device malfunctions causing him to lose. There could be limitations which prevent him from cheating completely accurately
Also, consider this: Nakamura knows that the position is good, but does he know it before he sees the evaluation, or after? Because it is a fact that when top player knows it is +3, he can explain why it is so good. But just looking at the board, without knowing the evaluation, he might have a very different conclusion.