In The Boy Who Drew Cats, why didn't the boy go home after he left the temple?

In this Japanese folk tale, a boy who is the youngest of many siblings is deemed by his parents to be too small and frail for farming and is sent to a temple to study with Buddhist priests. This child happens to have a particular passion: drawing cats.
The boy does not apply himself to his studies at the temple but instead continues to focus on his passion for drawing cats. When the priests of the temple see that the boy is not cut out for their way of life but has a special skill and purpose as an artist, they tell him to go back home so that he can pursue his calling. One of them gives him a bit of parting advice: to avoid large places at night and to keep, instead, to small places.
The boy, however, is ashamed that he has been sent away and does not head home. He wanders away instead. Needing a place to shelter for the night, he finds an abandoned temple and draws cats on its walls. He has no idea that a monster, a goblin-rat, is the reason why there are no longer any priests in this place.
Heeding the advice he had received to keep to small places at night, the boy goes to sleep inside a cabinet he finds in the temple. He hears frightening noises during the night. In the morning, the boy leaves the cabinet to discover a dead goblin-rat on the floor and blood on the mouths of the cats he had drawn on the temple walls. He is recognized as a hero by the vilagers.
In an older, traditional version of the tale, the boy stays on to care for the temple. In an 1898 retelling of the story by Lafcadio Hearn, he eventually becomes a famous artist.