The bone growing debate is a live one indeed. I was working as a coach with the Scottish Youth Climbing Team a couple of years ago and this issue came to light then, opinion is very split on whether it makes any difference.
If we wade through the arguments and counter argumnets though, we can simply apply common sense. At the time of the debate with the youth team, we looked at what we knew was good practice and what was safe and built around that. Grey areas are ok for lively discussion, but they don't improve performance. Take a positive approach, look at the opportunities rather than the restrictions, and get wired into it.
His desire to train and be healthy (and strong) is positive so you can look at ways to promote this in any way he wants. High reps, low weights will be great. Nice and simple full body programmes add a fantastic opportunity to teach him perfect form, how to structure a perfectly balanced programme and how to structure his nutrition around training.
Get him doing everything right, right from the start.
By doing this you eliminate any potential risks and give him a great base to take into adulthood -physique wise and knowledge wise.
<message edited by Bollard on 06 February 2012 09:55>