The Rust integration for Linux was invited and greenlit by Linus and Greg KH.
Because rewriting the kernel from scratch would literally cost billions. That's why. Literally criticising them for not achieving an impossible goal.
There are several kernel and OS projects as well, they get posted here from time to time. Doesn't stop people from coming up with some other slander in those cases of course.
As already stated, there are also Rust kernels being written - like they are in other languages as well.
Interesting how Rust makes some people so insecure. Already 2 levels in this thread.
People are already trying to make their own kernels in Rust. You just don’t hear about those because it takes a fuckton of time to build a useful kernel