Honestly since I doubt Kaku even falls under the category of legit arc opponent, my issue is why is Zoro not even allowed to look at Lucci? We know Zoro is more than strong enough to do so, but why is he boxed into this underling role where even the likes of Lucci aren't allowed to go near him. These are interactions that would actually be meaningful and Oda steals them from his readers.
I don't think Zoro vs Kaku is gonna be anything serious, but it's the fact that Oda thinks we care.....like the fandom is all hyped to see a cloutless underling with a giraffe zoan (most likely unawakened) that was one shotted by pre skip Asura, back.