Everyone has plot armor. Kaido was downright desperate to avoid getting hit and tried crushing Zoro, only to fail miserably. This is CoC and boneless Zoro to boot, so the excuses aren't gonna do much to help. Sure, Shanks definitely has a much higher AP than Kaido. Even post-CoC Zoro hits harder than Kaido on average, forget Shanks.
Zoro definitely loses to him. The point is, it won't be this bad because he already withstood Hakai's impact even when he got his bones scattered, and then went on to remain conscious from an attack that had Kid's rival Law on the ground. It's been also well established that Zoro's a much better fighter, as far as skills go, than Luffy's so-called rivals, meaning he's doing better than them against Shanks, period.
