[laumars]

You're right that Apple gets a lot of criticism for not supporting open source yet host a lot of open source projects. But I think a lot of the criticism comes about because Apple's commitment to open source often comes with caveats. To use a few examples from your list:

* XNU is based on existing open source software. You're right that Apple had no obligation to release the source of XNU given the permissive licences of the parent code. But equally it feels a little disingenuous to congratulate a company for releasing their code to a project that was open source to begin with anyway.

* Apple SMB referenced from Samba code and only created because Samba changed licence to GPLv3.

* Clang/LLVM isn't an Apple owned project. Though I will granted you that they are major contributors to it.

I cannot blame Apple for wanting to keep their proprietary inventions closed. They are a business after all so I'd expect them to put their business interests ahead of "good will".