I'm not a 100% sure, but I think he can only move from alternate universes on 'hypothetical days' OR days where he flips the coin and it lands on heads. I'm not too sure how the hypothetical days work, but he can travel when those days roll around.
(Take my explanation with a grain of salt bc I'm not too sure, but I hope it helped) (⌒▽⌒)
Cuz its too confusing....Im mixing things up like the one guy he left and the other guy that is present now. He should go back and not stay there. I mean this is my opinion but its heart breaking if he stays and not go back or being with those two..thats just being greedy if he cant choose (*but I do think he's going back*)
Is he not going back?? I will drop this one uhm