What makes you think he even considers Hibino a human that transforms into a Kaiju and not the other way around?
And what makes you think that?And I don't know why the writer felt clever about the part where asshole dad tells the scientists "those bindings are useless, he could break them and stand up any time he wanted". Yeah, WE KNOW. But why did nobody else in this show know?!
That idiot scientist didn't "know" (or perhaps just didn't want to break protocol), but why do you think they are in an underground facility with like 500m of steel all around them, if they had this "powerful chair"?
You should think a bit more about stuff from time to time.
It's so obvious that the father is a "purist" and that this is a very viable and emotion driven plotpoint you seemed to have missed entirely. That doesn't make him "dumb".
And the focus on that specific scene was actually the dad indirectly saying that he is stronger than that Kaiju, that was the author being "clever". Him asking "who do you think you are talking to" was not just about file&rank.