Man, it sounds like your friend got hit with a double whammy!! He went in for one thing and had a stroke because of the procedure! Sometimes, in stroke victims, the effects from the stroke are temporary, so I will hope for a total recovery.
Ultrasounds don't always show the stones, so if he is up flushing his liver later, I would tell him to do so. It's super easy, cost less than $5.00 and he won't have to go back to the Dr. for a follow up visit.