Another example of an issue that bears little to do with whether the student was left handed or right handed. The story is told as if it is one hand versus no hand: left handed people do lots of jobs with their right hand and right handed people do lots with their left hand. It's obvious that when learning to fly a particular aeroplane there will be a particular method that provides for the best operation of the aeroplane. If the above story is true then the instructor needs to spend some time in reflection.
I have taught a number of disabled people to fly: some without use of their legs and one who had only one arm. In each of these cases we had to spend a lot of time to find the method that was most effective for the particular individual for good reason.