If anyone is flying Luffy back it’ll be Momo, since Momo needs to overcome his fear of heights this arc and he’s the one who can actually sense where Luffy is.
I think it will be portrayed as Zoro returning the favour. “You helped me before, now I’ll help you.”
Perospero isn’t done, he still needs to run into Neko and Carrot again. And Oda did imply that he’s planning on doing something to Marco.
I could see a scene where
-Marco and King are fighting, Marco thinks to himself that even though he’s not fighting Queen anymore, he’s still tired from taking on them both.
-King gets set up to launch a heavy attack
-Marco goes to dodge, but Perospero sneaks behind him and encases him in candy so he can’t move
-Marco looks finished
-Zoro appears, blocks the attack, and tells Marco to rest and that it’s his turn to fight