I also have a 2020 and I have to say I am confused by your post. Does your kid love baseball or not? It's all well and good to have a preference for a favorite position but playing on a team is suppose to entail the whole concept of "Yes sir, wherever you need me to play".
We all gravitate to what we are good at, but your son will have more baseball options open to him if he can broaden his knowledge base. If he loves the game and wants to continue he should learn all that he can and become good at all that he can so he can be a more well rounded baseball player. What if his pitching plateau's? He's a 6'2 8th grader...he might be done growing, he might have peaked already and what he throws now is the highest he will ever throw...if he loves the game he needs to become proficient at more than just pitching to keep his options open. When multiple coaches agree he is a PO THEN he will be a PO, but until then just be happy to play.