You're still mixing stuff up.
Can Kaido decide to drop Onigashima right now? Yes. Can Luffy stop it? No. Does that mean he cannot fight Kaido? Of course not. What does that have to do with them fighting 1v1? Literally nothing.
There's no doubt King can just fly back into the dome right now and start molesting people until Zoro runs back and keeps him busy by firing flying slashes that force King to focus on dodging instead of attacking fodders. At least until King flies somewhere else once more. Again, so what? How does that help King beat Zoro in a standard scenario? It doesn't.
And from an inverse perspective King isn't stupid, he wants to fight and kill Zoro directly 'cause he's angry that he broke his mask. Really, if you start invoking PIS why didn't Kaido just slit Luffy's throat before sending him for a swim? OP doesn't work like that.
Fact of the matter is, having the ability to fly doesn't make you automatically superior to Zoro, it is simply another skill. It sure gives you the ability to run away if you desire. But is that alone enough to defeat Zoro? Nope.