More appropriate, the mother sounds like an overwhelming idiot
This kid may have been bullied but with his age, his IQ and a sudden change in behavior this should have shouted need for psychiatric intervention of some type.
On top of this this is maximal latch key kid. If Mom was working 70 hours a week this kid was alone an unsupervised most of the time.
I don't know how responsible she is in his death but she sure neglected him.