This isn't quite correct. Yes, it can output C code; however the result is not very readable at all, and fails the DFSG on generated code. It _is_ useful for compiling Zig code to targets which aren't supported by LLVM, however.
Do you have a reference for this? Does it use a C backend that is part of LLVM, or is it something Zig-specific? What are its limitations? Can it compile libraries to C, or only entire applications?
I have wanted Rust and Zig to support compile-to-C for a while, so this is exciting news for me.
One thing that would particularly interest me is if functions intended to be inlined could be emitted into .h files.