"I have even gone as far as getting some one-on-one instruction with his coach at the baseball academy to show my son that he is not some monster."
imho OUCH.
That's going to far the other way and if not handled right can lead to other problems with parents who know that you did it. I've seen this scenario not work out for everybody involved, meeting with the coach about your son is NOT GOOD. Perhaps I am reading too much into what has transpired, but if they feel they have to meet with you to effect his behavior he's got one foot out the door whether you feel its justified or not. CD gave some good advice. Mouth shut ----> move forward. It works at all levels of play and coaching from LL to pro ball, good coaches and bad coaches.
Your son has to find a way to make it work, sometimes you've got to try what the coach suggests, even if you know its wrong technique.