I mean, Mikolas isn't wrong on the general point -- there are rules on the books basically preventing hitters from stepping out of the box and stalling for time, and you could probably make at least a small dent in pace of play problems by enforcing those rules as written. And I appreciate that Mikolas is a work fast kind of guy.
On the specific point, though, Mikolas knows those rules are never enforced, he knows hitters are going to step out of the box in a way they technically aren't allowed to and so bringing it up in the context of a given game is pretty whiny.