Moderation note:
If he has current registration on the car in RI and it's older than 2000 it is legal to sell on a Bill of Sale in RI.
https://www.dmv.org/ri-rhode-island/...d-vehicles.php
If you are in a Title Only state that does not allow Bill of Sale only sales. You may have some difficulty or not be able to register this.
Caveat Emptor!