TechCrunch and Gizmodo just picked up the story:
https://techcrunch.com/2017/12/15/mozillas-mr-robot-promo-ba...
https://gizmodo.com/mozilla-slipped-a-mr-robot-promo-plugin-...
Also AFAIK the second link has the first official response of any kind? "A representative told Gizmodo the company is looking into the issue."