Defeating Omega Weapon = of course the only legal way to obtain the GF Eden
====
Anyway, back to topic: I believe this is just one of those numerous FF8 theories out there. I can't find the Ultimecia = Future Rinoa theory website...
As for the Dead Squall Theory, the Squaresoft team should have released a follow-up pre/sequel if the theory is indeed correct (like Advent Children/Crisis Core on FF7).