Earlier quoted context omitted.
As someone who has dabbled in OS development over the years, you'd be a fool to use anything other than C (I suppose you could use a restricted subset of C++ if you really don't want to write anything but a toy OS) or assembly if you have something to prove.
What about Rust disqualifies it? Let's say besides ecosystem immaturity (lack of libraries). As a non-systems programmer, I'm curious.
I'd be shocked if that isn't the case. I'm not saying that you can't build an OS in Rust or other languages, just that OS development is complicated enough without having to fight your language.