User blog comment:Tiredman2/Mass Effect Plot Holes and Contradictions/@comment-4953843-20120822075257/@comment-5337704-20120822122247

Chorban had a new device that didnt upset the keepers (making them kill themselves). He explains this part. They have tried to study the keepers before but they has something like a "turn off switch". Since the Citidel people know they have to rely on the Keepers, they made it illegal.