Malcom Gladwell is a popular journalist, I highly recommend reading books on this topic from actual historians. Gladwell wrote on all kinds of stuff and its nowhere near as well researched as what actual historians bring to the table on these questions. He repeats poplar myth type stories.
Learning about Japan, go to something like The Pacific War Trilogy by Ian Toll. It is new and well researched with lots of original research.
Gladwell's and Toll's accounts of the firebombing of Tokyo don't differ in any radical way.
Hell, if anything, Toll and Gladwell reinforce each others' point. Toll also goes on to explain that the same thing that happened to Tokyo happened in Nagoya, Kobe, Osaka, and pretty much every other major Japanese city.
I don't know about that specifically as I have not read Gladwell's book, I have just read a number of comments from people I tend to trust critical of some of his claims.
Learning about Japan, go to something like The Pacific War Trilogy by Ian Toll. It is new and well researched with lots of original research.