It doesn't. They're just saying that because the kid returns to Japan after moving to Hawaii, so people are equating that to returning to Kanto because, in the demo, it is mentioned that the player is from Kanto.
But there is no hard evidence, just speculation.
its also proven in the real games we moved from kanto is-well
plus japan is closer to hawaii in real life so kanto - alola is which they theroying