One way or the other, yes love brought him back. Olivia's memories resurfaced from the overwritten timeline because of her bond with Peter. No history was ever "selectively un-rewritten" as you put it, rather is was traces of the overwritten history that bled back through. The reason this hasn't happened for others is because Olivia's bond was with Peter alone and only Peter was removed from the timeline, his removal is what changed things. If Peter's absence was the only thing that changed then why would other people have resurfacing memories? Only those with connections to Peter should have any access to resurfacing memories triggered by his presence. Now why people like Walter, or Nina, Broyles or Astrid have yet to recover any memories prompted by Peter's reemergence may be because none of them have the added enhancement of cortexiphan.
I think a cool episode idea would be Walter overdosing on a combination of LSD and cortexiphan in some half-baked attempt to recapture memories from the previous timeline so he may restore his relationship with his son.