The younger brother is a hypocrite. Even with his growth so far, he's guilty of exactly what he hated in his older brother: that his brother didn't care about him. Like, it's good that the younger brother doesn't want to be a drag on the team. That's fine. It shows a care and concern for others. So he has the older brother replace him. However, it shows that even if the younger brother has started to care about other people, he still doesn't even care about his older brother.
Not once through this has the younger brother given concern for his older brother. The younger brother is still just jealous.