I was looking at the list of supported languages and found that SPOJ still does not support Rust as a language choice.
Rust has a growing community, following are Github stats related to Rust.
Rust-lang repository -> github.com/rust-lang/rust -> Stars(6935), Forks(1351)
Total github repositories in Rust -> 2179
Considering Rust is quite new and yet to hit version 1.0, this can be said to be a large community.
I suppose, we should consider adding Rust to SPOJ.