To me what was interesting was that even the CEO had to not only denounce it, but also cut his vacation short to hold a staff town-hall.
Most likely because, whether the author intended it that way or not, the memo was draft in a way that was pretty much guaranteed to push people's buttons. And when people -- particularly very smart people who have a lot more important things to do with their time -- feel their buttons being pushed, they tend to react, and get to the root of the matter very quickly.