I think I know what is going on here, based on a comment in Start of Darkness.
[SBLOCK]I think that the danger the Snarl poses is that something that is destroyed by the Snarl is destroyed utterly. If O'Chul is killed by the Snarl, he does not go on to the afterlife. He just ceases to exist. By leaving O'Chul near it as it expands, he expects the prisoner to give in. Hence the 'Safety of the Grave' comment; Being dead but in the afterlife is preferable to ceasing to exist.[/SBLOCK]
END COMMUNICATION