Much easier to build, for me at least.

I tried installing Rust and building the example, but then it complained about nightly features, and I didn't have time to figure that out.

C/C++ are mainstream languages, and building is as simple as g++ test.cpp.

If the point is to explain how green threads work, it is better to use a common language so people can simply try to understand the concept and not try to understand both the concept and the language at the same time.