That comment came about because of a licensing spat with the atheros source code.

http://undeadly.org/cgi?action=article&sid=20070913014315

It's worth remembering the full context to that incident. Earlier that year OpenBSD had been found to contain code that had been copied from a Linux GPL wireless driver project, in violation of the GPL. The Linux developers made a public mailing list posting about it and a lot of drama ensued:

http://thread.gmane.org/gmane.linux.kernel.wireless.general/...

Theo got very upset that the Linux devs practised 'full disclosure' over the violation and didn't contact OpenBSD privately (presumably he thinks customers who make use of OpenBSD should be fully informed about security threats that affect them, but not informed at all about legal threats that might put them at risk). He also tried to argue that the multiple commits over a period of time that contained copy and pasted GPL code was accidental, and got very upset when people suggested that one couldn't possibly accidentally copy specific portions of a GPL codebase and commit it to the repo multiple times. Theo also tried to argue that it wasn't a copyright violation since the code wasn't actually run-able (he knows full well that isn't how copyright law works).

The Linux developers response to that incident was also possibly partly motivated by earlier requests by some Linux developers for OpenBSD to dual licence portions of a different driver (i.e. also make it GPL). OpenBSD refused, for some of the reasons discussed already in this thread (they would likely receive GPL licensed changes that they would not be able to use). The strong reaction from the Linux devs was maybe to be expected after they had been told they couldn't use OpenBSD code, but then found OpenBSD had been stealing their code.

So there was a great big mess of egos and petty squabbling. I think a lot of that motivated the later copyright violations in the atheros drivers by the Linux developers that Theo is (rightly) complaining about above.

The point I think Theo is trying to make is in the open source world you simply have to expect that people will take code - put it under a different licence and modify it - restricting their ability to take back the modified code into OpenBSD.

Typically OSS licences allow and tolerate "selfish" behaviour. I don't think I or he needs to back up this claim with examples.

>that people will take code - put it under a different licence and modify it

Ok, although the 'take code and put it under a different license' is untrue, you can't re-license code unless you are the copyright owner, I gather that he means someone making modifications/enhancements and placing them under a license which OpenBSD can't use while remaining fully BSD licensed.

This happened when Apple adopted pf they added a few enhancements of their own but wrapped them in Apple's license so pf maintainers could not add the changes back into upstream pf.

This also happened with Linux's Atheros drivers (which were derived from OpenBSD, but modifications were published under the GPL instead of the BSD or ISC licenses; Theo argued that doing so was actually a violation of the BSD license (apparently they were stripping out the BSD license in the actual source files? I'm fuzzy on the details)). I don't remember what the outcome was.