Human physiology doesn’t work well on only fruits and vegetables, especially raw. A healthy person, even a child can live a lot longer than a week without eating. Unfortunately that boy lacked a regular diet of essential amino acids that are very difficult to get on a vegetarian diet. Even what nutrients that were in his food he couldn’t get to without cooking to break it down.
Our ancestors learned to cook their food to get the most possible nutrition from it. Earlier than that they learned to break bones with rocks to get the richest marrow. These things fueled the development of our modern brains and bodies. There is evidence our ancestors were hyper-carnivores deriving the majority of the calories and nutrition from meat. Vegetarians and vegan are fools thinking they can undo a million years of evolutionary development with their ideology.
And these folks weren’t even providing the children with nuts, which is a decent way to get some plant based protein.