Many do not understand this behavior, they cannot conceive the idea that an open source project can only be developed by a single man and lock the rest out. I personally understand Kurt, because I lived among people who are OS writters for a long time (and I even married one ;-), specifically, since 1995.
Writting a hobby operating system is all about a journey on gathering knowledge and having lots of fun in the process.
(late nights coding, lots of pizza, beer etc)
There is nothing more and nothing less into it. Hobby OS coders do not seek to overthrown Microsoft. They do not want to be the new Linus. They simply code to learn more and better themselves (which is proved by the fact that AtheOS has been re-writen in the past). If someone offers the code to you ('ready-made spinach pie' as we say in Greece), you learn nothing. If you just put together what different people have done at different times, it will result in confusion and bloatware, with no personal gain that fullfils the above 'dogma'.