Proof that he target a random non vital spot.
Since we have Law who guess that, we have the manga panel and point of his scar who proof that, literally everything point it out that Law was right with his guess, what is your point who speak against Law guess? Now explain.
Aoe or AP doesn't matter, the only thing we know that Kinemon was able to cut Kaido, with none adv user or special ability user could do.