Was a little bored with the daily, so I decided to replay mission 1 TTK, and during the cutscene, a thought occurred to me:
Mara Sov might not have been speaking about us escaping "that... pit". I recall a while back something from the Nine being involved. Pits and whatnot were mentioned.
Anywho, I assume it was directed at us being involved with Crota... but then again... it might not have been.