"Your heart cannot help but go out to the Banerjee family. By all accounts Aryan was a bright and bubbly boy and his loss in such a senseless way is unbearably sad," he said.
But the health and safety agency ruled Aryan's death was not something anyone could have reasonably predicted. No charges would be laid against the school, he said.
WorkSafe had not investigated similar incidents involving a window latch handle in New Zealand, Mr Stewart said.
"Yes, it was possible to foresee that someone might have found themselves stuck in the toilet. But it is not reasonable to think that the school or the worker involved should have planned to avoid the possibility of someone being so seriously injured climbing out a ground floor window and being caught on the latch."
WorkSafe met Aryan's family and informed the school about the outcome last Friday.
His death will now be the subject of a coroner's inquest to formally determine the cause of death.
NZME sk pd