And despite LLVM's and clang's history with Apple, it is most decidedly not an Apple project any longer. The LLVM foundation handles that. Looking at commits Google is a likely contender for the biggest overall contributor at this point.
I think this is a good example of mutually assured collaboration amongst companies. Sure some stuff gets split off and made proprietary, like the nvidia shader compiler, but overall more goes into it than out.
I agree with Linus on gpl v2 and gpl v3, v3 is off into the crazy territory. https://www.youtube.com/watch?v=PaKIZ7gJlRU
If anything I'd say this is an example of how taking too extreme of stances even if well intentioned, and I'll even grant them as "right on their own merits" can backfire in the end. RMS can consider llvm/clang an attack on gpl if he wants, but in the end I only see it as developers wanting to have improved tools and are willing to collaborate to do it. the fact that clang-format exists is a good testament to how gcc isn't doing itself any favors with its political stance in regards to being useful in other categories.
But all thats just like my opinion man.