Eh, in this case it's a tool created by Rust programmers for generating documentation for the Rust language, and has particular features for validation of Rust code snippets in said documentation. I think in this case, mentioning Rust in the description is reasonable.
Well, if it is implemented in Rust, then who cares whether it works or not? It's implemented in Rust!
The good thing is you don’t have to rewrite it!
I hope not since I use it as keyword filter in my RSS feed. Why are you bothered?
It matters in that it helps people contribute, which contributes to growth.