Christopher's Watching the Clock states that the factions of the Temporal Cold War didn't want to risk interfering with Federation history because of its role in the creation and destruction of the Borg due to the Caeliar/Columbia temporal loop--as seemingly every timeline but the primary continuity (in which the loop was maintained) involved the Borg overrunning the galaxy by the 26th or 27th century.
However, if that's the case, why would they meddle in Archer's life, given that he was close to Erika Hernandez, who's crew was responsible for triggering the sequence of events that led to the Borg's creation? I suppose destroying the Columbia before she disappeared would have undone the loop and prevented the Borg from existing, but none of the factions could predict how that would have affected matters on a galactic scale.
--Sran
However, if that's the case, why would they meddle in Archer's life, given that he was close to Erika Hernandez, who's crew was responsible for triggering the sequence of events that led to the Borg's creation? I suppose destroying the Columbia before she disappeared would have undone the loop and prevented the Borg from existing, but none of the factions could predict how that would have affected matters on a galactic scale.
--Sran