"The existence of LLVM is a terrible setback for our community precisely because it is not copylefted and can be used as the basis for nonfree compilers -- so that all contribution to LLVM directly helps proprietary software as much as it helps us."
See, this is why I hate Stallman's position on anything software. It's based on irrational thinking derived from a flawed ideology.
Since LLVM is not copylefted, EVERYONE is able to benefit from it, and that is good... FOR EVERYONE! For example, NVIDIA based their CUDA compiler on LLVM because it was not copylefted. Thanks to LLVM not being copylefted, NVIDIA was able to reduce their R&D time, provide customers with great technology, and consequently sell more products. The money that proprietary companies make from being able to incorporate non-copylefted software into their products has a ripple effect. Companies like NVIDIA can provide more jobs, LLVM developers become more highly sought-after, customers benefit from more rapid advances in the technology, and the entire LLVM-based community benefits from work that filters back down from companies like NVIDIA into the mainline LLVM repo.
Stallman's argument that projects like LLVM help proprietary companies take away users' rights is simply not true. There would be little benefit for a company like NVIDIA to take from the LLVM community, and be unwilling to give anything back. For one, it would be so much harder for them to hire good people out of that community, which they will desperately need in order to drive their products forward. But look at what has actually happened: NVIDIA are releasing the code to their LLVM-based compiler! Why? Because it doesn't really benefit NVIDIA to enforce a proprietary lock-in on their customers.
As for his argument against the Apple App Store, how is it really of benefit to anyone if binaries are "free" the way he thinks they should be? Does anyone really want or need the ability to install a "free" binary onto their iPhone/iPad? Why is wrong for companies to want to protect their proprietary platforms and technology (and also their users) from potentially malicious/illegal code, or code that might brick the device? Oh, that's right! Because Richard Stallman thinks that companies should not be allowed to guard any of their interests when it comes to software. This is an obnoxious opinion, and detrimental to real user freedom.
I do not think the world will suffer AT ALL if clang/LLVM has doomed GCC to irrelevance. I was actually glad to read Stallman's email because it signifies that clang/LLVM really are eroding GCC's relevance, to the point where even Stallman is feeling it. Soon, Stallman and his FSF cronies will be relegated to the footnotes of computing history where they belong.