More importantly, we foiled the Cult's plan, and Tzeentch's. After all, you can't take advantage of this guy if he got murdered by your Beastmen in a fit of spite because he didn't instantly succumb when caught in a bad position.
If we live, or worse--break--they get another throw of the dice.
Do what Trilby did, choose to [ ] Die, and in doing so, defeat the eldritch abomination lusting after you that requires you alive.