If you're targeting Go to cross-compile to, why would you build the language in Rust? Keeping to the go tool chain would reduce a lot of friction for those who are using go already, which I presume is a significant chunk of your target audience.
I don't work on the language, but I think building a compiler in Go (or C) is a pain in the ass compared to using a language that has discriminated union types, and based on the aesthetics of the language, the authors probably agree with me. The language is styled enough like Rust to make it seem like this is for "rust people" more than "Go people" anyways – I think if this was targeting Go people, it would use the native Go syntax for things like import (here replaced with "use") and adding methods, here replaced with "impl ..."
There might be an audience for disillusioned rust people who get bored with fighting the borrow checker etc, but true rust developers, like c++ devs want control and won't want to hand that to go's runtime.
My guess from the readme is that the author loves some of the rust features and syntax but the simplicity of having the go language and runtime take care of making it work is just too compelling. As far as the language itself, there's nothing here that you couldn't build with go and it would likely be more productive.
