A problem with the religious is that they are taught from childhood not to question or be skeptical of any claim made by their holy men. I'm surprised it didn't occur to anyone to ask him to dial back the risk by trying it on an animal first. At the very least, instead of it being a disaster, they could have had a delicious goat curry...instead of creating a widow with 6 children.
Yes, the healer was nothing more than a conman. He promised things he knew damn well he could not deliver. That does not discount the stupidity of the follower who enabled his own death by volunteering in the first place. Maybe he is happy he is in his promised land.
"You can't fix stupid." About all you can do is hand out Darwin Awards. Look, if your dumb enough to think that a preacher with no medical experience is more able to save your life than a doctor, your about one brain cell away from forgetting how to breath anyway.
Though the healers have a great amount of influence over their followers, the followers are still human beings. They have free will. They should be held accountable for their actions. If they believed in something wrong they should be held accountable when they do something wrong. Blaming the healer is just an out.
Ultimately, people should have free will, and if a volunteer makes a conscious choice to participate in something, it should be on their own shoulders. You can't make other people responsible for the desires of other people. I do think it would be ideal for there to be a written contract that clearly states the circumstances, but as long as consent is fully and freely given, nobody can be held responsible other than the individual who GAVE that consent.