Imagine the horror of Chaos' existence if Hojo had kept him for himself, or put him into the alien-hybrid-mess that would become Sephiroth.
Indeed! Heck, imagine the horror for the Planet if it would've had to deal with a Chaos Sephiroth... though I guess Chaos would've lent his powers to Sephiroth less willingly than he did for Vincent... but still. (Ironically, one of my crack!artbunnies that likely won't get realised any time soon due to my lack of drawing skills was for Chaos Sephiroth and his counterpart, Safer Vincent.)