When Kaido said it he looked rather confused, that basically means that he wasn't rlly sure that it was CoC. And for Kaido, who spent almost his entire life with CoC users, to sound confused about CoC isn't normal. My point is that Zoro didn't use basic CoC but rather CoC coating hence Kaido's confusion. Why would Kaido sound confused because a rookie used CoC when the new world is full of CoC users?