Oh My. Thought I better update this no matter how embarrassing. He thinks he figured it out.....
So he removed the battery cut-off and it happened again while his girlfriend was driving and stalled the car. He thinks his girlfriend was more than likely not pushing the clutch in all the way! She is a new manual driver and has short legs!! Waiting to see if that was really the only problem!! Glad he's a good kid cause I racked my brain on this one, Thanks for your help Mark. Will let you know if this happens again.