Aaron(2) has been confronted by Aaron(3). The information and ideas he expressed has not only given Aaron(2) advanced knowledge of the future but also, and more importantly, he has learned how to avoid that future. He will not simply go back in the box, disappear, and reappear as Aaron(3) to repeat the same mistakes. Instead, he wants to go back and relive the past few days and at the same time, take the steps necessary to prevent not only Granger's appearance in the timeline, but Aaron(3)’s as well.
Aaron(2) goes back. He does not drug Aaron(1) this time. He has convinced himself that if he can prevent Aaron(3) due to their confrontation, that Aaron(1) could do the very same thing to him. By doing this, Aaron(1) should become a Houdini, leaving Aaron(2) to do as he pleases. He is sure that Aaron(1) will find the fail-safe, become the early version of Aaron(2), go to the party, and eventually disappear for good.
However, Aaron(1) will only time travel if he escapes from the attic, follows Abe to the U-Haul, and finds the fail-safe running. Fortunately for Aaron(2), as he will later figure out, Aaron(3) is already in the timeline. He was there before as a silent observer to Aaron(2). He may have even drugged him, taken his place, recorded the day, and gone back, erasing his memory of being drugged. If Aaron(2) decides to stay away completely during these events, then Aaron(3) will find, not Aaron(2) at home, but Aaron(1). Then, it will be easy for Aaron(3) to drug Aaron(1) and put him up in the attic. That poor guy, I hope he is not allergic to fiberglass insulation.
