If your son wants to play HE has to go and speak to the coach, not YOU. Stay out of it.
I am willing to bet that his attitude and arrogance did him in, some players think that they are so good they can act anyway they wish because the coach will never let them go. Obviously that isnt true. And obviously the coach doesnt want his attitude to rub off on the younger players.
Sounds like your son may need some growing up, maybe this will be a good lesson for him.
Blaming the coach on ruining his recruiting chances just does't cut it for me.