Rust is competing with C++ for writing low level systems, whereas Clojure is designed for writing business applications.
Low level systems tend to have stable and well understood requirements, whereas the same cannot be said for business applications. Efficiency is not a primary concern of business applications, but flexibility is. The efficiency of Clojure is often "good enough" for business application, and there is no peer in flexibility. This explains the many fintech companies using Clojure, as well as many other B2B companies.
Also, Rust binaries have been of comparable size in the past. Check out this question where someone asks why Hello World is 3mb even in release mode:
https://stackoverflow.com/questions/29008127/why-are-rust-ex...
This 3mb doesn't have any cached heap, doesn't have any garbage collector, doesn't have support for high quality exceptions and doesn't have much in the way of a cross platform abstraction, whereas the Clojure-as-native binary has all of those and more.
There's a giant pile of things you can do here to try and reduce Rust's binary size:
https://github.com/johnthagen/min-sized-rust
... but as you can see, it's a lot of work.
Rust gets great press and HN is flooded with "let's do it in Rust" type comments. But I think sometimes we need a reality check. Rust is an extremely different language to most others, even C. The combination of the borrow checker+everything async is not obviously better than everything else, not even in the low level domains even though Rust is deservedly picking up loyal users there. The moment you care about development speed i.e. for the sort of apps Clojure was designed for, you're going to be better off with a GC and a strong runtime that abstracts the platform well.
I'm almost sure the author would drop the project as soon as he realizes and lives the frustration of not being able to come anywhere near close to the performance of Clojure in the JVM.