I think the piece fit the situation's violent, and utterly insane depiction. You've got Sephiroth going out of his mind, trying to kill and dismember an alien as he calls it "mother," and just when he's about to do his thing, Cloud comes a long, mad with rage and anger, and skewers him.
But that isn't enough, and he lives through a Buster Sword to the back, and then stabs Cloud in the chest.
But THAT isn't enough, and Cloud lives through a Masamune to the chest...AND LIFTS UP SEPHIROTH BY THE VERY SWORD IN HIS CHEST AND FLINGS HIM INTO A MAKO PIT.
I mean, if that isn't utter insanity, and disjointed chaos, I don't know what is.