I think he'll have a problem getting a Doctor to certify this, and you have to consider how fair it would be on other road users, never mind pedestrians, given that he gets distracted etc. Maybe call his GP and have a quiet word about his condition and his intentions, this might make it easier to deal with. Insurers will likely also have a problem with this, and for the same reasons. He is required to disclose anything that is relevant in his insurance application. A condition known as "utmost good faith". Given what you have said, they will likely ask for a medical report.