I think that this is both (1) a big deal for certain people and (2) not as big a deal as some people try to make it.
Rust is a young language. It takes time (and a certain kind of external pressure) for a language to be standardized. C took roughly 19 years. Rust is only 11. I think it's perfectly fine to say "yeah, if you're doing something where a standard is required, Rust might not be ready for that yet". It doesn't reflect poorly on Rust.
At the same time, applications which require the use of a particular version of a particular programming language standard are pretty rare, even in contexts that require high reliability. Reproducibility of builds is better guaranteed by simply refusing to update, and reliable behavior by writing thorough tests. I've heard more people hand-wringing over Rust's lack of a standard than I've actually heard of people who wanted to use Rust but couldn't because it doesn't have a standard.
To the question,
Does your employer actually care about language standards? Or do they care about creating robust, performant and maintainable software? If it's the first thing, you shouldn't try to sell them on Rust, because they don't care about it. If it's the second thing, the non-existence of a language standard probably isn't the make-or-break factor. Let's not forget there are still plenty of reasons not to choose Rust that don't have anything to do with standardization.
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