Quote:
Shuyin (FFX-2) and Genesis (FFVII: CC): When bad guys feel like people I went to high school with I feel we have a problem. Shuyin whines around about a lost love despite the fact its his own damn fault they got killed and still feels the world should pay? Whiny loser is more like it.
It's stated by Maechen, the best source we really have on Spira, that she would have died anyway thanks to Bevelle. Either that or she would have been sacrificed as a Fayth like the other summoners.
Besides it's not like Shuyin told her to come there. She came of her own free will. If she hadn't, he could have started up Vegnagun and killed everybody and she be fine.
Also he's quite right in his assessment.
"...Spira hasn't really changed at all. Everyone's still fighting over nothing; still dying like they used to. A thousand years have passed and they can't leave the hatred behind."
So his reason for destroying everything is also reasonable.