Rust does have GC in external crates, one was used for implementing Lua in Rust.

A Lua interpreter written in Rust+GC makes a lot of sense.

A simplified Rust-like language written in, and compiling to, Rust+GC makes a lot of sense too.

A simplified language written in Rust and compiling to Go is a no-go.

Well if you think Java doesn't have a sufficiently good type system, then surely Go is even further from one?

Not saying those are the only two GC languages, just circling back to the post spawning these comments.