Children pay no attention to buddy discipline. They do such silly things. They would torment him by ignoring his instructions when diving one of the local wrecks. There's nothing you can do under water. Nothing too unpleasant, of course, but I think it's quite good to get a bit of a shock.
Teenagers are likely to forget things - like doing deco stops.
We have to take things like decompression very seriously, because we can't treat emergencies on Mustique. Lichfield is a great believer in the salutary lesson. It may not be pleasurable, but it's very instructive, like the first time I felt myself getting a touch of nitrogen narcosis. Knowing your limits in everything in life is important, but particularly in diving. He has had his share of frights.