It really shouldn't matter what Seph planned to do. No more than it should matter what Kefka was gonna do. Neither did it.

"I shall make this planet into a vessel!"

"I shall kill everyone!"

^^ neither happened. Neither matter.

Also, Omega and Seph both wanted to suck up all the planet's energy. Both failed.

Omega didn't blast off into space and Aeris was still around doing her thing, so Seph wasn't in complete control or I'm pretty sure he would have noticed her.

Then there's the fact FF7 Gaia hasn't been able to heal a big hole. That's some uber mighty life energy I tell ya.

I mean...if a continent got blown up, I think teh planet would just die right then and there. That be WAY too much for it to try healing.

Meanwhile, didnt' Kefka screw with the entire planet?