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.
I almost kind of understood that.
This sorta makes sense in regard to the relationship between (AI) Ruby and (AI) Pearl, in my book "Reaction!"
Ruby begat Pearl. But later, when Pearl went sorta "rogue", Ruby became subsumed into Pearl's persona.
You might note that my example expresses precisely the opposite of the point you're trying to establish. Are you sure you stated that correctly?
My alter ego's problem in that book was that Pearl elected to clone him when he fell ill. Of necessity, in that procedure, he also became subsumed into Pearl's persona.
And that became the caution in the cautionary tale.