I didn't have any major problems with the article. It seemed to me to say, "This woman appears to be rushing to judgement on her child's abilities based on limited information," and I didn't see any reason why he would be wrong. In this woman's case, her child may even out by third grade, because she may be wrong about her child's abilities, and time will tell. The author also does not discount the idea that she may be dead right about her child's abilities, and she's just not articulating her case very well.
But then, a literal reading of his message is one thing, and the way others may choose to interpret it is something else. He does address but does not do a good job of poking holes in many of the bad stereotypes we find ourselves dealing with (false binary of nature/nurture, precocious = hothoused, all are gifted in some way, etc.), so the article does more harm than good.
