Correct me if I'm wrong, but ClojureScript is implemented from scratch and independently of "big" Clojure. If it is so - to run Clojure on other systems you have to implement everything, which makes no sense at all.
I find it quite annoying that for a language that is meant to be "parasitic" there is no simple way to port it to any target. There are a few Clojures around that target e.g. C, but they are more "lookalikes" than the real thing. And ClJS is a separate codebase.
It would be cool if Clojure was one and the same thing and then had a backend to support generic platforms - this way you would have ClojureJVM, ClojureNET, ClojureGO, whatever, with different levels of support and speed, but at least you could share the code. For example, maybe the Go version could have only :aot and write Golang sources.