What timeline? He can't live through it the same as before anyway. The first time through, he was first seemingly the hero, allied with the human side, including the main girls, but betrayed them. Now he's living in a totally different manner. Not to mention the girls themselves will be acting vastly differently, seeing how they retained their memories. Yet the scenario requires the girls must stay alive. The last time the MC actually killed them or personally saw that they died. There's no timeline to speak of. He might know the identities of most of the important folks and maybe some events that's aren't in any way tied to the so called main quest, but a whole lot of things will be utterly different, no matter what. Not to mention the scenario will keep giving him information and quests.