Oda is smart af. Oda had planned Zoro to be out of commission when Kaido started to come downstairs to the main floor after he knocked out Luffy. Marco out here trying to defend them and you have others coming in to fight. No Zoro and heck not even Sanji. He made sure Luffy is getting the main spotlight here. Otherwise I feel like Zoro, Sanji and Marco could have teamed up and took him on.