The Borg were not involved in the Temporal Cold War, so it could be that they were indeed supposed to be there for history to play out the way it does in Daniels' timeline.Because Star Trek:Enterprise sucks and any story around it should be ignored.
At the conclusion of Star Trek: First Contact, the presence of the Enterprise-E and its command crew, along with the Borg, had become part of the "Prime" timeline events of April 4, 2063. The "essential" event of Cochrane's warp flight before 11:00 am, NAMT that day, occurred, sufficiently preserving the timeline--and in fact, in the corrected, Prime, timeline, this would never have occurred without the Enterprise-E crew's help. We refer to the timeline as having been "changed back", but what that means is "essentially changed back"--when the timeline is "corrected", or "preserved", there are, by definition, always ancillary, non-essential (hopefully) events which become part of the new, "corrected" or "preserved" timeline. In this instance, these were: (1) the presence in Earth orbit of the Enterprise-E; and, (2) the presence in Earth orbit of the Borg; and, (3) the Borg's attack on the Montana missile complex; and (4) the destruction of the Borg and the crash-landing of the Borg Sphere in the Arctic; and, (5) the Enterprise-E crew repairing the Phoenix and its launching and support systems; and, (6) the Enterprise-E crew interacting with Cochrane and Lily and the lasting effects of this in their lives after April 4, 2063 and in the lives of those they subsequently told about their experiences; and, (7) Riker and LaForge's presence in the cockpit of the Phoenix as they and Cochrane conduct the historic warp flight; and, (8) the Enterprise-E's departure from the twenty-first century and return to the twenty-fourth century. Repairing the timeline is about essentiality, not complete repair to the point of it being that the repairing agency was never there.
Here, it is true that the timeline implications of the discovery and excavation of the crash-landed Borg Sphere remnants rippled into the ST:ENT 2150s timeline, but Daniels going back to April 4-5, 2063 just to ensure the total destruction of the Borg Sphere remnants that had crashed in the Arctic, in order to erase the occurrence of the events of ST:ENT "Regeneration", would make for kind of a boring story. If these remnants had never been excavated, the subsequent events of "Regeneration" would not have occurred, but the Borg awakening would still have occurred much later, as glacial movements due to climactic change uncovered them naturally.
Most importantly, it was never established that the constituent events of "Regeneration" constituted an "essential" event resulting in a substantial change in the timeline, necessitating Daniels' intervention ProfessorTrek 09:11, August 6, 2011 (UTC)