There is no such thing as security critical code. If it is out there - it can be expoloited. There are a lot of stories with minor exploit chaining leading to huge compromise.
Rust is a nice language for greenfield system software project. But everyone in the software industry knows that you can't just put a project on hold and rewrite completely in new language.
I can't see anything good coming from this initiative.
There is no such thing as security critical code. If it is out there - it can be expoloited. There are a lot of stories with minor exploit chaining leading to huge compromise.