Agreed.
Frankly, that's the only point I care about. This argument is going down too many side-paths. So let's keep it nice and simple. Aerith was the one who was a threat in Sephiroth's opinion, and in conjunction with Holy, she saved the planet. Remember at the end of the game, when Holy couldn't destroy Meteor, the Lifestream (led by Aeirth and others) rose up to help Holy destroy Meteor.
I consider it the latter.