Being unsure whether a guy who is 40 or 41 can run under 2:20 when his best performance in recent years was a 1:07 half over a year ago isn't discounting someone's ability as it is a statement as to my uncertainty about his ability. Those are different things.
That being said, if asked to wager money, I would have bet that he wouldn't have broken 2:22; so he did prove me wrong for sure.