sinnoh is too big to be put into this game
the overwelming refs. to Hoenn (Dive Ball works on underwater Pokemon now? come on...)
to answer your question, the Reason i think its a link to Hoenn is because if you think about it, how in any kind of way can the Creation Trio fit into the main story line? they can't, but what they are basicly telling you is that Ghetsis has no need for them, but it tells you that Ghetsis is collecting them, then he runs off some where, i think Rayquazas gonna play a part, but i could be wrong, we have basicly no info so we can't really call anybodys theory dumb.
oh i would love to see the Creation Trio in the game, Dialgas up there at number 3 for my fav legends, it looks awesome!