I must said it, I don't like the way where Oda is going on with this. I don't mean the 1on1 Luffy part but how Zoro never was praised by Kaido like he did with Oden. In fact I was sure that Kaido would at least said lines like: "So their is a another monster Samurai as Oden" but he didn't and the scar feat became underwhelmed for me. Hell like Cinera said Ashura get outshined by Luffy in the same chapter and that is a massive problem. Somwhere I hope for Zoro to get back but as you pointed out, seems like Oda want for him a second battle with a calamity. Great for Luffy, but disappointed for Zoro.