My thought about it is that Bruce Wayne doesn't relive different past lives, but instead had to find a way back to the present using a variety of time travel devices...ala the 1950s style Batman adventures where he was sent back in time on various adventures by Professor Carter Nichols. What if this is a sneaky way of bringing Batman back through time AND also ensuring that those wacky time travel stories in the past actually happened.
Personally, I'd love for Batman to knock Dave Knight in the head and take over as Starman in Opal City for a month.
- l.k.