Ah. This I understand. Time is mine to play with, both past and future.
"The past is prologue ..." -- No, no, no. The past is backstory, whose only purpose is to shade and limn the beginning of the tale.
And that foggy port we call the future; that is waiting for our dénouement, the revelation or ravelation of our purpose, and the meaning behind it all.
I can fully imagine everything the HabWorld inhabitants doing having some impact on the past in some fashion in such a way that it directly causes them to begin their journey in the first place.
That said, postulation on nanotech subversion: the rule of firsts, a mind once already present within the object to be suborned cannot suborn the object again. I.E.: If your mental imprint is already present prior, you cannot take whole control. For example, you are an AI, and you try to wrest control of the person/system that created you, you cannot as you are already in there.
It would be like trying to open the door by closing it.
As with all rules, there are exceptions.