I don't understand a thing here . Atleast it doesn't make sense here. Aramaki said that if kaido is around he wouldn't have come here. So did aramaki came to capture luffy who defeated kaido. Only way this makes sense is that Aramaki thinks that the guys who fought two yonkos will be injured situation and can be taken advantage of. Otherwise i would not see greenbull coming to wano where the powerhouses who defeated kaido and BM is present. Also makes sense why he retreated just as he felt shanks. We thought Aramaki to be reckless but he is purely a cunning one . So this still states that yonkos are atronger than admirals.