They already have node which is a mix of javascript, C++ (v8) and c(libuv.) Go is a fine language, and it's ok to want to write infrastructure code in go, but they shouldn't be giving false reasons.
Sure, node.js is implemented in multiple languages. But when people talk about writing code in node.js, they mean writing javascript. It's a javascript runtime, after all; it says so right on the front page of https://nodejs.org/en/ and even has js in the name. :-)
Saying "of course node.js supports multiple threads of concurrent computation, you just have to write in c++ instead of javascript" is missing the point of why people use it.
