This isn't quite how Outside Fate works. Rather, at any given moment, precog would show the future as it would be if Taylor were to vanish off the face of the earth right then, and everyone were to forget her.
So whatever plan Simurgh had for Noelle, her precog showed it going perfectly, right up until Taylor exposed Noelle early, at which point her precog would have shown the consequences of Noelle being found early without Taylor being present (probably a lot higher bodycount), And then it would have shifted again when Taylor killed her.
Now, from Simurgh's perspective, the future is wobbling violently either way, but she doesn't think that Taylor is still gearing up to be Skitter. That strand of fate has already been ripped out. As far as precog is concerned, Taylor does not exist.
Basically, Taylor can steal the proverbial horse shoe nail, and precog would show the kingdom winning the war, right up until the nail is stolen, and then it suddenly shifts to showing the kingdom falling. But it wouldn't show what happened to the nail, other than it suddenly vanishing.