I'm going to play the part of a stan -
He's four years old! He's not missing anything. They are caring parents. Literally THE best. How DARE you question their decision-making? Their children are loved, cared for, well fed, and spoiled, and if they want to take him out of school even though he's been out of school of three weeks already, that is up to them and who are you to judge? You're just a jealous hater! Why are you even on this page?!?
Sound about right?
You're exactly right.
Forget structure, engagement, socialization, classroom assimilation, motor skill development, consistency and organization in life, etc.
Trackers need to take him out of school to AK and push the other miracle off on a nanny.