Did you catch the sleight-of hand, there? The dude put the mortar on his head, lit it, and "the accident happened". What accident? The lighter worked, the mortar worked, it was sitting right where he wanted it. Every thing about the whole affair was as on purpose as it gets. Dude killed himself as surely as if he'd stepped in front of a train or suck-started a twelve gauge.
Lady, I'm sorry your kid was an idiot and paid for his idiocy with his life, but just because your kid thought he could breathe water is no reason to make the other kids get out of the pool. Normally I would not speak so to a grieving parent, but you are trying to use the force of law to inflict your grief on everybody else, and that is most uncool.
An idiot-proof world is only fit for idiots. Just sayin'.