If it aids in predicting things, then it could help. For example, if he’s mentally ill, then people can stop holding their breath that he’s going to suddenly reveal that he’s actually superintelligent and has been driving trollies the republican party deliberately (a theory I heard someone trot out recently). And in the scope of his own life, if he or his loved ones ever want to help him, then knowing if he’s mentally ill can steer them towards therapies that are more likely to be effective than, say, trying to debate him out of his current state.
