That's a wonderful story and and an uplifting rebuttal to Lord of the Flies. But to be fair, six Tongan boys were probably far hardier and well equipped than the typical British schoolboy of that time would have been. It seems they thought nothing of stealing a fishing boat and heading to sea, and they most likely had abundant life skills already - they basically relocated from life on one pacific island to another.…
Thirty years ago I saw recording of a heated interview with William Golding about the character in the book the boys should have chosen to lead. I can't remember if it was Ralph vs Piggy however I think Golding argued that it was Simon, the Christ like mystic, who would have provided salvation for all the boys if he was followed. Simon represented altruism in the book picking hard to reach berries for the smaller boys who couldn't reach. So in real life when a group of boys who are stranded on island who have religious values, altruism like in the case of caring for the one boy with a broken leg it is like they would have chosen Simon as Golding suggested in his interview to lead.
It might not be a rebuttal to the Lord of the Flies. It is a confirmation of what Golding said about the boys and their values.