no good deed goes unpunished.

as a retired lawyer he knows what he is doing and taking advantage of you. he sounds like a toxic person and probably doesn't have many friends.
give him a deadline to be out and stick to it. have him call his son to pick him up then say-la-v-lavern.

just a FYI. if a unlicensed person gets into a car crash there won't be any insurance on the car. even if there is a valid policy on the car.
i am no insurance expert. the ins co might cover damages on what the car hits. but there probably won't be any coverage on the car he was driving.
i have seen this multiple times on wrecks towed into the body shop i work at.