Correct me if I'm wrong, but it looks like this is using the mlua Rust bindings (which are excellent). It's not a Lua runtime from-scratch in Rust. It's the regular C Lua/LuaJIT with a Rust interface.
I would describe this as a Lua wrapper written in Rust. That carries the clear indication that you should not expect the interpreter to be written in Rust.
I would be (and indeed was) disappointed to see that this 'Lua runtime' did not have a Rust implementation of Lua. I would be much more interested in seeing that than a wrapper.