Probably even Oda recognized he was too much of a clown when he draw the Luffy vs Kaido fight and now he is trying to patch it.
Also probably he doesn't want to troll Lucci the moment of his reintroduction, even if he had no problems with Greenbull, that is probably because at this point there are too much admirals in the story, so he used the last one to hype Shanks and his movie, who knows.