I agree with most of his comments, even if they are a bit naive. But for the most part he's correct - Gentoo likes to change things far too frequently.
If you take the time to read the comments (85 at time of writing) you'll find that most people are at one polar extreme or the other W.R.T. supporting or hating this guy's conclusions. I'm more towards supporting the guy (I'm a Red Hat/Fedora supporter anyway), but the worse part is that the people that are disagreeing with him are just downright cruel. They flame/troll and come off as being even more ignorant than the OP - if I was reading this article to determine if I wanted to use Gentoo on a server, I would come to the conclusion that the user community is made up of a bunch of childish know-it-alls that I don't want to have a part in (ie, I would not use Gentoo).
For the people that are knowledgable and support Gentoo without flaming the OP, most of them only maintain 4-10 servers running Gentoo. That's far too few to be able to claim that you can maintain a farm on Gentoo. There are a couple that seem to have the build-process down and are running it on many, many hosts, but there's a lot of infrastructure work that needs to be done in order to do that, and due to the flexibility of Gentoo I doubt that it could be reused at any other organization (think policies that would have to be assumed for a build system - security updates, binary packages, dist-cc, or compile-per-machine, etc).