There's nothing in the article that says there were safety concerns about him eating or swallowing. Not having had lumps in the past and only having two teeth aren't reasons to only give pureed food. Maybe more will emerge and it will turn out that he was under medical care for his swallow, in which case yes of course the nursery were negligent, but there's nothing in that article to say so.
Don't get me wrong, I wouldn't want my DC at a nursery that didn't follow my wishes about something as fundamental as food, but giving food the parents don't agree with isn't in the same league as giving something unsafe or an allergen.
I'm going to leave it there because I don't want it to seem like I'm criticising grieving parents, I remember their comments around the change in ratios and really admire them.
I just think we should just all be very very careful about saying someone is responsible for the death of a child when we don't have all the facts.