He was taking Apoo serious though, and also hacked up by Hybrid Drake. A Yonko would have flicked Apoo away like a bug.
That's why I said, it's circular logic to push King so much because of Zoro's performance against Kaido. Note that Zoro scarred Kaido with adv.CoC which he used unconsciously, while against King, he probably won't use it. And he might beat King in a similar fashion to Kaku, which is far from extreme diff.
Yet he wasn't going all out. Mihawk was taking Luffy seriously..it doesn't mean he was going all out.
But Zoro isn't a Yonkou so what does that statement prove?
It isn't circular logic to claim simply because King's performance will determine his level... that is basically the valid logical approach.
It would be circular logic to claim;
Zoro blocked Hakai but couldn't block King
so King > Hakai...etc etc
However here we have direct comparison when it comes to wind scythes.
King also has his own feats and hype from Marco.
Obviously haki is yet to be used so there's no definite way to conclude where King actually stands