Do not know WHY people report Rust and Servo as serious Mozilla projects. Yes they will be what they claim to be, HOWEVER they are not officially backed by Mozilla, nor are they destined to replace code already in use (as opposed to eg. IonMonkey which was from begging “offical” succesor to earlier works).
Look at text of news. No link to official Mozilla site. Just github link :D
Mozilla is big organization (not company :P), and rigor about what you can do is not so strong. But do not affiliate with mozilla projects that are not official.