I get the feeling he's just acting but damn I love that Minoru is even capable of displaying this kind of attitude now.
Let's not forget that 3ish years have passed since he first became a national champ at the end of his series, and all the while the legendary Hamada Kaoru has stuck with him. He's actually Ibuki-tier as a fighter now, as evidenced by the bonus chapters at the end of volume 6 of this series (so, half a step below Samart, maybe?). I do think the "looking down on others" is merely acting, but the confidence itself is totally justified