He definitely used CoC but whether or not it was CoC coating specifically is pretty ambiguous. I said this in a previous post but I think there are three options:
- He used a much weaker version of ACoC compared to King of Hell considering there were no visual effects
- He unconsciously used a burst of regular CoC
- Ashura itself is somehow a manifestation of CoC
The main reason Zoro fans deny the use of ACoC on the rooftop is because some people will come in and say that Zoro's scar on Kaido represents the max damage that CURRENT King of Hell Zoro could do to Kaido, which is a pretty dogshit take