But it should be done in style, which Ribbons lacked. If you're going to get people to do your own dirty work, at least have a personality while doing it.
However, it dosn't really work in this case. The build up of the rivalry was more hinted to than presented dramatically. And having a mono e mono fight between the two seems rather unusual climax for an indirect rivalry. Its better to defeat the chessmaster at his own game, instead of punching him in the face.
Although, I do have to admit, Setsuna proving to be the real deal was very statisfying and one of the high points of the battle.