He may also want to consider moving the gun to the opposite side if he carries a cane.
Pretty hard to draw with something constantly in your gun hand.
This is a good point, especially he needs the cane for support all the time.
I've shot several USPSA matches using a cane in my left hand (right knee was gimpy). When my left knee got gimpy and I had to use the cane in my right hand, I would have shot matches lefty had I been able to attend any.