i'll agree with that.

its a game.

i wasn't too sure about kuja destroying the crystal and yeah. it makes sense that he doesn't but necron is an entity without the need of a physical body.

necron is not evil. he has no alleigance. its only his job that matters and it would be pretty stupid, considering what his purpose is, if he could actually be killed.

i take it you understand that kujas ultima killed the party (please say you know this. i'd hate to explain this too.) which is why they appeared at the hill of despair. if you dont believe this...

in short: beat trance kuja. notice how the bodies of your characters dissapear as if they've evapourated and been completely destroyed. and then they appear at a completely different place that is no where near the crystal world. it would be harder to prove that they are alive than it is to prove their dead.

anyway. it was a sort of a between life and death battle of will.

necron says this exactly.

"Why defy your fate?"
"Is the will to live that powerful...?"

which sounds a lot like him realizing something.

after he realizes that he is not needed, he dissapears but of course, he will return.