Maybe the guy you're replying to edited his post, but "If it's a JavaScript framework, please give code examples in JavaScript"--to me--reads as a rather polite request, rather than a dictum as you suggested.
There's no mention of CoffeeScript anywhere
It's in the 2nd paragraph of the docs. Not prominent, but somewhere.
CoffeeScript is not JavaScript
Technically true, I suppose, but they are beyond related.
If it's a JavaScript framework
Maybe it's a CoffeeScript framework? My sense is that at the very least, the use of CoffeeScript is an important aspect of the project.