Currently in Escalation, Halsey is still against the UNSC and both parties are at the Absolute Record. However, in the opening cinematic to Halo 5: Guardians, Lasky tells Osiris that Halsey has contacted them and is willing to give them information of the strange Forerunner attacks. I wonder what happens in between the Absolute Record arc and the game, your theories?
I won’t try and guess what occurs between the current issue of escalation and Halo 5, but I will say that Halsey never seemed to really be on the Covenant’s side. She was probably only using them and Jul as an asset to follow the Librarians instructions, answer mysteries, and help give Humanity as a whole an edge against the Covenant, the new Forerunner threat, and possible future adversaries. Therefore, when she learned about what was happening to the colonies and how the occurrences were happening(presumably the Guardians), she realized the threat and advantage they posed, and so she contacted the UNSC so that she may warn them of the ensuing danger or events. Also, it can be assumed that her presence is becoming irrelevant to Jul, so she is beginning to feel threatened and to put in simple terms, she wants to be rescued even though her rescuers aren’t the ones she wants to be rescued by.
Hope this helps 