Man, I am really sorry that your son was forced to make such a hard decision due to the actions of one dullard of a coach. However, I think that being able to make a decision for ones own well being, in spite of immense external and internal pressure, is one of the hallmarks of being a real man. Sounds like even at that early age, your boy proved himself to be much more of a man than his short-sighted "adult" coach. Must be the good bloodlines !
The other issue you raise is kind of a scary one, ie your son being concerned that his weight cutting could have been stunting his development. I have never heard this issue definitively addressed by a MD, but I know our club coaches and I have talked about kids they have seen over the course of 4-7 years on the kids circuit. A number of these boys who are fighting to maintain weights under 90 lbs for several years in a row really do seem like they are being "bypassed" in natural size by there same aged peers, even after hitting puberty! THAT is scary to me, the idea of screwing with a persons long-term metabolism just so he can be the most experienced or strongest 75 lb 14 year old in the state! Yeesh!