It is not reasonable to bag on Gladwell because some ignoramus cites him as scientific fact. Your problem is with your boss, not with the "negative externalities" caused by an author who writes something that makes your boss do something else dumb.
It would be a different story if Gladwell wrote an article exhorting bosses to hand out "maven" badges. But he did nothing of the sort.
It depends on your ethical theory I guess. To my mind, Gladwell's actions have predictable negative consequences and he should be held at least somewhat responsible for those consequences. Of course he's free to write what he likes, and I am not arguing for censorship or judicial intervention. But I think he has a negative impact on society and argue against him on that basis. He is the same as the "visualising higher dimensions video" or homeopathy, or any pseudo-science -- using the right words to get the answer you already thought of. I just love jerf's response to the video I mentioned (http://news.ycombinator.com/item?id=1385736) and I'd like to misquote it here:
I can not anti-recommend Gladwell enough. He is anti-knowledge, convincing you that you know something when you actually understand it less well after reading than before.
It would be a different story if Gladwell wrote an article exhorting bosses to hand out "maven" badges. But he did nothing of the sort.