So he went for a 5 MILE DRIVE, ON PUBLIC ROADS, to check if he could drive ok - rules said you shouldn't drive ANYWHERE unless it was essential.
Rules at the time said only QNE trip for exercise was allowed per day, not a nice wee walk in the woods where you couldn't GUARANTEE that you wouldn't meet anyone or leave traces of virus that could be picked up by others (even they shouldn't be there either) or that you won't pick up the virus that might have been left (illegally, of course)by others. No matter how unlikely you think those possibilities are.