But Atlantica has an actual reason to be in BBS. I can't think of any KH1 or KH2 world that has more reasons than Atlantica to be in BBS. They need to explain why Triton knew of Keyblade wielders and why he disliked them in KH1. Every world in BBS is connected to KH1 somehow, and Atlantica has a big connection to the past, the fact that Triton knew of keyblade wielders and disliked them shows that something happened in that world with other keyblade wielders before KH1 so TAV should go to that world and do something that makes Triton dislike keyblade wielders and then we have our explanation.
The game actually went by a time line and there was a mapped out time line in the 358/2 days ultimania. The worlds all followed the same time line through out the story. Therefore proving the worlds all follow the same flow of time.
To me that proves nothing.
The time can go at the same time, yet go slower in Disney worlds. And for all we know, Disney worlds are ageless. Look at Disney Town. We went to the past in KH2, but the characters were there, only in their old designs. And in BBS it's there too. They haven't aged, just look different based on the time they were created. Ah you know what I mean.
An ageless world can have a same timeflow, yet not having characters age.