There is a reason it should come from the player. Well there are many reasons. Should the player have to? No. Should a coach no better? Yes. By the time a player reaches the HS ranks he needs to be taught how to handle his business. Sometimes that means keeping his mouth shut and taking it. Sometimes that means speaking up for himself and standing his ground. And all the time that means he should do it in a respectful manner. It doesn't matter if the coach is a clown or not. That should not determine how you handle the situation. It just means your going to have to handle some situations.
I can certainly understand your anger and your emotions in a situation like this. It should not have to be dealt with because it shouldn't happen. Yes ball players are warrior's. We teach them to be warrior's. We want them to want the ball. We want them to say I got this. But at the same time they need to know how to stand up for themselves in situations. "Coach I want to keep going. I want to battle it out. But I'm done. You know I am coming off TJ and just threw a ton of pitches. For the sake of the team I need to hand it off to someone else."
The coach can handle it anyway he wants to after that. But at least he knows that he can't do that to him. Maybe it will jar him into reality? Maybe it will make him think about how stupid he was? But regardless he will know that your son won't be that guy. And now you won't find yourself in a situation like you are in. Again I understand your reaction. You had every right to be ticked off. Just a suggestion.