{original post had no questions}

Yes. Up until that moment, the total forces available to the
shadows were an unknown to us...sort of like Shroedinger's Cat, is it
alive in the box or is it dead? It could be either one. If they
didn't go into the past, didn't affect the outcome, it would be one
reality; if they did, then it'd be another. As soon as they achieved
one or the other of those two, the two possible results collapsed into
the one, singular possibility.

jms