Klein is neither a conservative nor a liberal in a knee-jerk sense. "Primary Colors" was anti-clinton, but not a full-bore indictment. If nothing else, he knows how to sell books.
I agree that UN employees are not likely to read this book in the lunchroom. But what may seem hopeful to some of them is that the UN is not fundamentally corrupt, only taken over by a faction that might possibly be forced out.
Of course the huge majority of UN bureaucrats are simply products of a system that milks the US and uses the money to dole out gravy to the US's enemies. They are probably sympathetic to the program Kofi represents. And Kofi was by no means the first, just the worst.
Well, I wrote that before I realized that there may be two Joe Kleins. The Time guy only seems to use the name "Joe Kline." So far I haven't been able to find his full name. Maybe a little more research. . . .