I'll be honest, I much prefer Left-Hand Mutant's way of taking out the Storm Rune over Sir Stompy's, if only because there is a sanity-check involved. A likely failure state in destroying the rune by using an LFE not only leaves behind the burnt-out rune but
also leaves behind a seal, which
absolutely confirms a ninja/sealmaster's presence. Noumero commented on the potential dangers of Akatsuki being notified of our involvement above.
@Sir Stompy, I would caution you to use a sanity-check/optimize on the Declare to ensure we put the best possible "destroy this rock" plan forward.
EDIT: Actually, what's stopping Hazou from prematurely detonating the Storm Rune with a Remote Explosive Rune, modulo the risk of runic failure?