That doesn't fix the problem: these languages has to be able to coexist peacefully with C in the same address space. You can have a dynamically linked library written in Rust in a host program written in C, you can use C libraries in Go, etc.

Even if that wasn't an issue: this is a bug in C as well! You should absolutely be able to use setenv/getenv safely in multi-threaded C, it's insanity that you can't.