Either way, he's screwed. I'd like him to languish in prison for the rest of his life - totally isolated, knowing he failed, knowing he accomplished nothing, and maybe let some interrogation take place

. If it leaves him lobotomized, who cares. Nobody will ever know.
On the other hand, if he dies at the hands of infedels, his twisted soul will be tarnished. No paradise in the afterlife for you!