I mean, you can argue about It for both.
What made me believe he wasn't a Yonko during that time was the story but of course I used It for Mihawk because I found really inconsistent what Shanks could be a Yonko during that time.
Now Mihawk could have become a Yonko too? Happy for the guy, at least now you have credible proofs for your agenda, before that chapter I found the arguments weak, he didn't really shine at Marineford.