There's an ongoing discussion about potential adoption into upstream, though.
The thing here is: it would be harmful if we, Ferrous Systems, claimed or even be confused with a more general Rust spec. That's a) the privilege of the Rust project and b) problematic if consumers were to understand it that way.
Doesn't Rust have a Reference manual already? A "spec" just wouldn't be very meaningful given the lack of independent implementations. But to the extent that the reference manual doesn't suffice for documenting the language, that's a defect which could and should be fixed.
The manual isn't directly consumable by formal processes. The compiler design doesn't have to be influenced by a specification, but it does have to be described by one.
The thing here is: it would be harmful if we, Ferrous Systems, claimed or even be confused with a more general Rust spec. That's a) the privilege of the Rust project and b) problematic if consumers were to understand it that way.