Get off the kid's back. He was psyched to run the 100, he got his shot, and all he did was crush the world record w/ the potential to put it in the stratosphere. What he is doing is amazing, especially considering the fact that most guys his height don't have his fast twitch abilities. Most are long striders who don't have his kind of explosiveness. He's just being a kid. Now, if he did something like get in the face of an opponent and taunted them (I recall a basketball player once coming down from a dunk and mockingly acted like he was crying for the opponent; real classy), then I could understand people getting up in arms.
Not everyone has that "act like you've been there" attitude in sports. We see that in gymnastics now: the athletes have done a good job of maintaining poise while the media and even their own coaches whine and complain like spoiled children when things don't go their way.