I thought you meaned Clumsy in what we saw, not in how luffy used it.
But thanks, you proove that Luffy used it and we don't see any thunder following, Same for Zoro, Roger.
Once again, in both examples you mentioned regarding Luffy and Zoro, their use of Acoc was clumsy at first, and only later were they able to use it correctly. That's the simple reason behind it. Similarly, since it hasn't been stated anywhere that Kuzan has basic COC or is using Acoc, he doesn't possess it. It's as simple as that.
Can this change? Of course, if Oda declares it in the next chapter.
Using Zoro as an example, a Zoro who was unaware of even having basic COC, let alone Acoc, doesn't change anything, as I mentioned before. Zoro and Luffy both used Acoc clumsily. Zoro demonstrated it during his Ashura attack, where Kaido even asked Zoro if he had Conqueror's Haki. Luffy, on the other hand, was rough and clumsy in his use of Haki, as confirmed by Kaido himself after defeating him.