Perhaps he means the tooling for using emscripten with rust is superior, and easier to get set-up? (i'm not actually sure if it is, i've never tried it). I'm really excited about the future of rust and have really enjoyed writing a raytracer in it, but I don't see how it's an easier-to-use language than C or C++. Easier to write safe code in sure, but not easier to pick up for a newbie.