I'm not arguing that you're wrong - to the contrary - I'm answering your question to the how: If you really want to use Rust, and there is no second compiler or at least an -O0-like bootstrap compiler to compile a compiler, then you have to build said compiler and use it.

I simply read all this as "in the current state you cannot use it if you have any meaningful security requirement". But the compiler isn't even the biggest problem: Cargo is. If besides the compiler, you also have to audit every diff of every release of every crate you use, would you still use Rust? Would it still be as great a language as the bird app cult likes us to believe? Have you tried reviewing crates? I have; results vary.

Remember "we have reason to believe that libsecp256k1 is better tested and more thoroughly reviewed than the implementation in OpenSSL", and GMax explaining it a bit. If we take this as baseline Bitcoin developer mindset, then we can be pretty sure that we need some effort put into rust if we really want to use that.