Oh, come on. The dude just spent 20+ minutes with Drake and countless fodder trying to get the antidote back from Apoo, while Apoo was holding them both off at the same time. You think he's going to go from needing Drakes help to finish off a Supernova quickly, to soloing someone like King who >>>>> Apoo?
If Zoro is going to go from fighting King to joining the fight against Kaido, then he's getting help against King.