I loved this mail, and it's actually making OpenBSD stand out as a human project, because it's not riddled with indecipherable political correctness. You can feel there are people involved, that they didn't copy-pasted a template but actually thought out their words, you can feel the involvement of the people. On the other end of the spectrum a smiley would also make the project more human, closer to the people. This mail also serves as a warning to future people who will want to engage a similar path of "I don't know anything, but I think things should be done This Way" to actually think about it. A net advantage.
Yes, the mail is harsh; that doesn't mean countrygeek should have a problem with it. The latter can (and should) absolutely go back to the research part, try to understand what he asks for, and then come back with a plan. That is what is really asked from the kind of people in the same position.
"Hi guys, I know you've been working for years on this! I haven't really bothered to look at your code, or understand the principles of operation, but I have strong opinions about How Things Should Be Done and I'm here to tell you how to run your project."
The reason Theo himself replies to this sort of thing, and in this sort of fashion, is to make it absolutely clear (both to this imbecile and anyone who seeks to emulate him) that the people who want this sort of thing are wrong and will be wasting their effort in asking for it.