The kids always did like a bit of dramatic flair, and hey, if they think he's dead, it'll stop them from asking inconvenient questions when the other Foretellers finally arrive. So he makes sure to expel the part of the old coot right after he falls over the edge, before following a corridor right to where he's been keeping the box for safety.

They never think to check for a body, and one of these days, it's going to be a hell of a surprise for everybody when Luxu comes back from the grave.