Alas, Patch 8 has eaten this piece of cheese! Now any pickpocket attempt on Orin breaks even Greater Invisibility and triggers the cutscene. This leaves the more difficult attempt at Lockpicking the altar instead of stealing the key, or my earlier plan of casting Globe of Invulnerability on the prisoner (which often gets Orin, too, depending on where she stands) and then setting off the Runepowder.
