I don’t think it is. That way, you have two authorities checking things over instead of just one.
Edit: I'm not implying anything about the capabilities of this preference-updating system; the subject was software updates and who is trusted to deploy them.
You have completely misunderstood what Normandy does.
I cannot understand how anyone could think otherwise of Normandy.
I trust my mother; it does not mean I trust you, and even less the entire crowd here on HN.
I've stopped using Windows years ago because I didn't trust Microsoft anymore. I'm having minor trust issues with Canonical and Mozilla. I still trust Debian and Arch.
Trust is personal. Hard to get and easy to lose.
This has some limits -- it largely applies to systemwide, not user settings, user dotfiles are generally outside of scope (though are also typically unmolested), and some packages, including Firefox, manage to introduce their own configuration management schemas and misbehaviours.
But yes, the general idea that software updates do treat user and local configuration as sacrosanct is well-established, decades-old practice, in at least some parts. And goes a long way to establishing and sustaining user trust in those systems and their update processes.
Mozilla face numerous challenges, including a large multiplatform largely non-expert userbase operating in an overtly hostile environment. The whole browser extension regime is a very unsatisfactory compromise itself. There remain lessons which might be applied from Debian.
I know when my Firefox updates, so I can expect changes.
My Firefox is vetted by my Linux distribution.
This is the first time I have heard about Normandy, and I certainly would not turn it on, because I prefer my work machine to be a laggard than an early adopter.
Only the trustee changes, so I still can't parse your concern. You don't trust Mozilla to RECONFIGURE (!) or REPLACE (!!) your software unbidden. You trust Canonical or Red Hat or whoever. And that changes what?
That concern just doesn't parse. If you don't trust Mozilla to give you working software, why are you running their software in the first place?
There are circumstances and concerns where you might want to limit things like software and preference updates. And both of those are and remain under your control. But the default is to allow updates, for obvious reasons.