. . . It is true that Oathkeeper represents a paopu fruit. You have to give him that. They may not have shared a paopu, but they share promises to see each other again, galvanized by the Oathkeeper trinket, and still have a trace connection due to her time inside of him. (If that sounds wrong, I'm sorry, but she WAS inside him)
Since promises are so important in KH, you could say that they've already effectively done what the paopu was meant for, without actually sharing the paopu fruit. Part of the premise of the BHK is that the ordeal in Castle Oblivion made him forget Kairi, and it seemed to me, with that forgotten promises thing at the end of Reverse Rebirth, that he may not remember his promise to Kairi. He most likely will, though.
In short, I think they don't need to share the paopu because of what happened to them and their promises.[/QUOTE
well really i doubt the fruit will play a big role, i mean they have there promises, and actually the oathkeeper represents a promise more then the fruit (hence the word oath) i mean yeah maybe the fruit but more of a promise