But surely this Didact (can't remember his exact name, like the Iso-Didact) wouldn't want his Cryptum opened by a human, considering his utter disdain for his greatest enemies (bar the Flood)? Also, why did the Prometheans attack the Chief, if they were under the Libranian's control? At least, that's the impression I got from the terminal, where she raises her hand, and all the Prometheans turn blue in colour.