Within this arc, Luffy, Kid, Zoro, Killer, Big Mom, and Kaido himself have all noted that it is impossible to damage Kaido with conventional means, with Luffy, Zoro and Kaido explicitly or implicitly referencing barrier ryuo.
If Oda wants to retcon the fall damage (which I'd say that while hyped to not really damage him, did some minor concussive effect, not real damage in the first place) with his more recent fleshed out content, then he will. He has been inconsistent with the way Luffy's blunt damage worked pre-skip many a time.