That doesn't inherently prove that it was Yhwach himself that slapped up Kenpachi during that encounter.
"He was defeated by Yhwach" isn't a contradictory statement against the assertion that Royd Loyd was the one who slapped Kenpachi up instead of Yhwach himself since Royd Loyd was physically disguise as Yhwach at that specific point of time, which would be perfectly in line with the statement "He was defeated by Yhwach" because he was defeated by "Yhwach", it was just Royd in disguise as Yhwach.
It also takes more assumptions to claim that for some reason the real Yhwach came out of nowhere to slap Kenpachi up, than proceeds to dip compared to the assertion that Royd Loyd, while disguise as Yhwach slapped up Kenpachi on his way to fight Yamamoto.
It would also contradict the fact Yhwach was specifically talking to Aizen at that point of time while Royd was doing his stuff, you'd have to assert that Yhwach stopped talking to Aizen just to do this action, than teleport back to Aizen to continue the conversation they were having previously. It just doesn't make logical sense in comparison to the claim that it was Royd Loyd who dicked on Kenpachi.
Arc7Female proving once again why she's a Reio victim smdh.