It says he was given B12 supplements and a diet at 14 but didn’t stick to it, the comment about dislike of textures yet chips, crisps and bread are all different textures. I think the parents need to take responsibility here
I don't see how you think they could have forced a 14 year old - almost certainly bigger and stronger than his mum - to eat things if he simply wouldn't? Do you think the parents of anorexics should also force food down their throats?
This case is horrible and very sad, but I think there must also be an element of bad luck or other health issues, because such terrible diets aren't that uncommon and while it's never good or healthy, it doesn't usually have consequences as dire as this.