I don't mind people rewriting things in <insert-name-of-tech-I-like> but "modern" as a value seems pretty loose, and it's often at least arguable whether it's objectively better!
Usually the hyperbolic superlative for Rust projects is “blazing fast”. Of course, any kind of benchmarks or comparisons with other implementations are completely optional. It is simply enough to “cargo init” and start hammering out code. You don’t even need to consider the characteristics of the algorithms you choose to use! If it’s Rust, it’s “blazing fast”.
It’s bad form to badmouth someone’s earnest work for sure. I wouldn’t do it normally since I think it’s nice that you actually did something. But if you’re going to sit in a glass house and throw stones you should expect some back.
Fortunately, my house is an underground burrow so I can throw stones with impunity. As ugly as it is to do.