A lot of players his age are going through the same process, making similar decisions. Most college pitchers were some of the best HS players in their area as both position players and pitchers. They had to make a choice at some point or it was made for them. During the recruiting process, it typically becomes more and more evident where their best opportunities will be and they have to weigh that with their personal playing preferences along with many other factors in choosing their college path.
If the signs are telling him his best opportunity at the next level is as PO, then he has to start figuring out whether he will be happy as a college pitcher. It is a lot of work and if he can't buy in completely to that direction, he will likely not make it too far. If he is convinced that he wants to play at the college level as a position player, that's fine too, but he needs to understand that he will likely have to focus on and step up that part of his game and/or be willing to accept playing at a lower level (or two) as compared to what his potential seems to be as a PO.
You are correct that baseball isn't supposed to be a job in 11th grade and should be fun. But the reality of today's competitive college landscape is that if he wants to play at the next level, there is a heck of a lot of work involved for him (and most aspiring players) right now, as you and he are experiencing. IMO, finding the balance is the key. If he is absolutely set on playing at the next level as a position player, and he is not the typical teen that may be inclined to change his mind in a few months, then I agree - he should consider a change (or a discussion with his current coaches) so that he can pursue his true passion.