If he can't get it switched, he may want to try what I do. I've always shot righty guns left handed. I flip the safety with my middle finger. I have my trigger finger on the guard and flip the safety when the birds are in the air. Plenty of time and it just feels natural. I even have an auto 5 that I shoot this way. Works fine. It would probably be easy for him since he's just starting to shoot left handed.
Keep the trigger finger just inside the guard, but not touching the trigger. Middle finger wrapped around. This way, you don't have to bring the trigger finger back around.
I was always concerned that someone else would pick my gun up and fire it thinking the safety is on if I had it reversed.