I certainly would not have walked out on young players trying to play the concertina, I applaud Noel Hill for the tuition he gives to players. Young players learn the basics and then formulate their own styles based on what they like. Whatever Noel has taught them will set them up for life. Just in the same way Dick you and I are offering tutors to help players learn the instrument. If you introduced five youngsters that cloned your playing I would stand and applaud their efforts and congratulate you on your advice to them.
A classic example of this is Kate McNamara a superb Irish Concertina player that has been tutored by Mary McNamara (no relation). She has taken all that Mary has to teach her and added her own style to it. In exactly the same way that the Noel Hill youngsters will develop their own style.
Al