Hmm, yes, I understand why the Unladen Swallow developers, and to a certain extent Google, would want to do that. It just seems to me that the community would benefit more by waiting a little.

By the developers' own admission, LLVM's JIT infrastructure is immature and integrating it with Python uncovered lots of issues. Sure, clang has pretty good community support, but that doesn't mean that the Python integration - or even the JIT stuff - is equally well-supported. And the Python community doesn't contain many LLVM experts, I'd wager.