Earlier quoted context omitted.
Perhaps the (you won't be signed out of your Google account) language was something an engineer or product developer insisted on. Perhaps they figured that was their part, and that it's up to the rest of us to take 10 minutes and switch to Firefox so data-driven Google knows this was a bad idea.
Mozilla are winding down their efforts to make Firefox competitive. They are not planning to make a full servo browser anytime soon and they are transfering resources to VR and other things. This is disapointing. You can't blame them, their user base is in free fall.
> Our long-term plan is to:
>
> Incrementally replace components in Firefox with ones written in Rust and shared with Servo
I don't know if they have a date in mind for the delivery of a 100% Rust Firefox, but they're not stopping the initiative.
The page goes on with a list of stuff they planned to add to Servo in 2018, which will eventually go into Firefox.
Edit: fixed the formatting of the quote