You think Luffy ran out of CoC when Kaido dropped him off the Island? @Celestial D. Dragon
But to your Initial point Zoro is still referring to Enma that's draining his Haki. Enma acts on a whim and randomly pulls too much Haki and Zoro is just being cautious.
Tho its possible Enma can keep taking Zoros CoC but Zoro is fine but Zoro is not aware since Zoro is not aware its CoC he's using?
There is also the fact that Enma has already taken too much Haki from Zoro on roof top.
Idk at least gotta wait for Viz but I am just gonna say Zoro and Luffy are low top tiers