Do note that Mozilla is not a hive-mind, and people disagree with Brendan on a regular basis. I haven't heard of anyone within Mozilla who was actually interested in NaCL/PNaCL/dart.
Do you think a systems/application developer, who believes in those ideas, would choose to work at, or be a part of, Mozilla, given Eich's clear and verbose positions that stand entirely apart from decades of success shipping consumer applications for desktop and now mobile devices?
As someone who writes consumer applications, I want a common application platform, but I'm not going to sacrifice my tooling, work quality, or user experience to contribute to a fundamentally flawed approach, just because it's "open".
NaCl and Dart were both created in a Dart room without anyone else's input.
Google at least understands the flaws. Web developers seem to have their head in the sand while mobile may very well eat their lunch.