So he didn't reject you because you were a poor student, but for some other reason? Sounds like you might want to consider what you could have done differently to improve on that outcome. Regardless of whether you agree with what s/he tells you, it's a chance to gain some valuable insights into what others think about you.
Apparently, I was pretty obnoxious in high school. It took me far too long to learn this. (And to learn when not to speak my opinion.) I would have been well served if I had swallowed pride and asked teachers (and peers) for some perspective on how my attitude was, frankly, self destructive.
What was his public reason for doing so?