he denied causing the earthquake. he never denied using CoC. read the official translation. also look at the artwork for zoro's panel in 997 and luffy's panel in marineford from my post.
I am looking at the official translation now.
Brook: is it haki? The supreme king? What have you done you beastly man!
Zoro: you know I didn’t do this.
It’s clear Zoro denies using CoC. And don’t talk about the drawing. Look at the context of this chapter, the earthquake happens later Black Maria says “So impatient” afterwards Yamato says it’s Kaido’s doing and on the last page a confirmation from Kaido to have moved a whole island to the sky.
It’s obvious. Let’s not force something that doesn’t exist.