I'm not sure why you think this is a problem that Rust has? Perhaps you mean something different but the Rust project compiles available code on crate.io upon the release of a new version.[0] C compilers may imagine their new compiler code doesn't break old software, but Rust takes that extra step, so we know it won't.
Now, the Rust kernel is currently using beta and nightly features which are on track for inclusion in the stable Rust compiler. So, yes, right now compilation is tied to a specific kernel version, and may need to be updated if a feature changes. However, any C compiler used to compile the Linux kernel uses non-standard GCC extensions only recently adopted by clang. Imagine if the C standards committee chose to change the syntax/sematics of a non-standard extension. Do you not imagine the non-standard extension would also be similarly deprecated?
The issue seems to be Rust is telling you what is non-standard, and you're yelling "Look it's non-standard!". But consider that the kernel in practice is using lots of non-standard features, and should the C standard simply adopt this non-standard behavior that means likely having to changes lots of code.