Gladwell gave examples in which he absolutely murdered the pronunciation of the number 7. I'm not talking about tone problems. He pronounced it as "kwee". It was clear that he hadn't even bothered to listen to the number words that he devoted a section of his book to.
Of course I don't expect someone who isn't a student of a language to speak it well, but he could have at least gone to wikipedia or chinesepod and listened to the numbers once or twice!