Anyone thought they should've...? (spoilers)
... left the kid?
The kid seemed pretty satisfied with his developing friendship with the girl, he's not as excited to leave the town and he obviously loves visiting the loving grandfolks. Also, he barely knows his mom and she herself probably has serious psychological issues after three years in jail. Not to mention that they can't speak Spanish and have no contacts in Venezuela.
The only downside of staying would be if something were to happen to his grandparents, the possible teasing of kids (although he already dealt with that) and never seeing his dad again. Sure, it's tough, but the position he's in now might be even tougher for him in the long run.