The push to use a language comes from the mindshare, and Rust is more popular than Zig, D, or Ada. There does seem that some boundary was crossed: the attempt has decent manpower, and is being taken seriously.

I also think you've gotten the wrong impression. "if its not written in Rust, it should be" is rather wrong, no one is suggesting to replace Python with Rust. Instead, there's a spirit of "if it's written in C, it should be replaced with Rust". Since a lot of free software is written in C, I can't blame you for generalizing.