I really think you do not need to feel sorry for your friend. They are his kids, it is his duty to pay for their education. I bet he enjoys to go to his son's graduation ceremony and his daughter's piano rehearsal. At his age, having a good relationship with his kids becomes much more important than having extra money to indulge.
All the expenses you listed for the daughter (piano lessons and etc.) seem reasonable.
As to the son, I don't know. I would think a 22-yr old should not take money from either parent anymore. Even if he still has to pay, it won't be long, another year? Your friend will be fine.