You slightly misunderstand the power scaling. Pitou’s “feat” to display their strength is not them defeating Kite. Pitou’s biggest feat to scale them is when the King attempted to kill them and he said he struck with his full force. Without spoiling, the King will soon have plenty of feats to more accurately scale him and you can then scale the Royal Guards based off that but even without his future feats it’s pretty understood that the king is insanely powerful, so Pitou just eating a full powered attack from the king with nothing more than a bloody lip is proof enough of how powerful Pitou is. In fact the king literally says this in that same scene.