Rust is currently developing so fast that this bullet point in the manifesto is nearly obsolete. C/C++ currently still has the edge for multiplatform-support (emscripten, PNaCl, iOS, Android(?), game consoles), but that's about the only remaining point. With Rust it is also easy to integrate existing C libraries (e.g. middleware libraries for game development), which is usually the main problem when choosing a language other them C/C++ for game development.