I had him working on my HCIM, who had 99 firemaking and 90 agility, among a few other stats working on Wintertodt trying to get the tome. He killed my HCIM, as he said he had lost his internet connection. He's offered to rebuild the account, it'll take weeks to get to the stage it was at before, so I'm posting to let everybody know. I'll either delete/update this post if/when my HCIM has been rebuilt.
-- I was incredibly clear that he was not to do anything dangerous if he felt his internet connection, skills, and/or knowledge of task would put the account at risk. He ignored it.
EDIT: He has completely ghosted me. Has ruined my account and ran off. No word since.