I don't think anyone is arguing Zoro won't take damage from Kaido hits. But he'll still be far from heavily injured from a single TB if Law can get up 4 pages later and then tp down before proceeding to run after BM.
TB >>>>> casual swings. Nothing suggests otherwise, CoC or not. It's a named attack.
Zoro is not getting so overwhelmed to not use Ashura lol what kinda head canon is that. If he gets sent flying once, he can retaliate immediately after. Zoro has shown enough speed to blitz Kaido even after warning him. Quit downplaying him.