I don't know the details of this case, but my guess is that she smoked heavily when pregnant, he was born with the craving and that she allowed his "habit" to develop as soon as he could crawl and get to grips with the ciggies/lighters .
Shocking neglect, but as long as the SS do their job properly and focus on the child, not the mother, he is probably better at home as the care system is in such a shambles. I would remove a child automatically for deliberate violence/cruelty, but neglect is a bit more ambiguous.