It would be equivalent to him walking, re: speed and general safety. Hell, it's a pink "car", which is great for visibility! It's nonsense to charge him with a DUI. They gonna do the same to someone drunk while in a motorized wheelchair?
Also, this whole situation is just an extension of our stupid car-centric societies: the damned sidewalks stopped existing on his path to the store. He was otherwise just fine using the sidewalk until he couldn't. That's neglect on the city's part.
Edit: downvote all you want, the cars were a danger to him, not the other way round.
Terraria. It's $5.