Cope Mald Seethe and Cry
Zoro trashes Big Mom
It's obvius Oda hasn't given Zoro the narrative place to trash a great pirate like Big Mom; his place regarding those leagues is just a consolation prize right before he falls defeated in front of Kaidou. He belongs to the 1.39b subordinate (a threat level that will only keep seeming smaller and smaller as Oda loses his mind with bounties) as one of the actual great pirate's wings, that's his place: second fiddle. And no psychotic interpretation of "power levels" you may make will ever change that, because no matter the crap you come up with, the narrative is simple, clear as day, a message 95% of readers end up getting is that an emperor whose defeat put Kid and Law among the big names of the world is too much for Zoro, King and whatever person who isn't actually among the top of piracy right now.
Again, just read the narrative. Zoro will one day be up there, one day he will be capable of defeating Big Mom. But not now, it serves zero narrative purpose for Oda's scheme of things. Defeating an emperor isn't a matter of whose slash is bigger but of milestones; and Zoro's current milestone wasn't an emperor but an emperor's subordinate.
Thats exactly what he's doing. If he didnt care he would have BB defeating Ray or vise versa. Having BB using coa first time against the SSG is to show us, the audience, that they are not pushovers and powerscale them between YC level.
Blackbeard has a human body. A weak sea monster took Shanks's arm, Squard pierced through Whitebeard's whole chest, Jinbe used CoA first time against some Charlotte fodder and of course a slash would have hurt Teach if taken directly. Heck, I bet you could stab the guy if he existed in real world, the blade isn't breaking upon touching his skin as if he's Kaidou, Big Mom or freaking Bobby Funk.
And of course he cares about not having Rayleigh nor Blackbeard defeated here, but not because of some power level crap.
