Two words - shoe bomber...
There is a wide middle ground between saying "Oh whatever, go on through." and making him take the braces off and walk through without them. Common sense would be to take the family to a private area to have the braces removed and examined or put through the scanner.
There is - the TSA officer was not properly trained. If I were a betting man, I'd say that he was probably fired over this...
What they said. Yes, it could have been handled differently but we weren't there and we don't know if the family gave them a chance to handle it differently. It could have been that the dad went off on the guard as soon as he suggested the boy take off the braces and the guard just didn't understand how serious his condition was--we don't know because you know the press is so unbiased and reports everything exactly the way it happens

On top of which, I am sure YOU have never made a mistake so it is difficult to understand that someone else might make a mistake OR that person was just doing what his boss told him to do. It isn't like they hire rocket scientists to be airport screeners.