Had the pleasure of working with Alex while at System1. Great guy. If I remember correctly I got one tiny change merged into Waterfox that's probably since been undone in the years since :-).
Did you read the same article as me? The word is singularly used in the context of how do you earn money as a project, i.e. sustain the effort. It's a bit of a leap to imply this is impure unless they made some contract stating the opposite or are doing something dark.
> Waterfox’s approach of allowing text ads on the default search partner page is our own decision for sustainability
"Sustainability" indeed.
Firefox has already done so to google, and when a fork is big enough, they certainly will hear the siren's call.