As long as FF takes Google money, it’s tarnished.
As long as FF takes Google money, it's less money going to fund anti-web activities.
The difference is the majority of national parks funding might not come from highly-pollting industry. Mozilla corp would not survive for long without Google's bribes.
Mozilla has to keep paying the bills. I expect most people would be upset if they starting charging for the browser or selling ads, and I frequently see complaints when they focus on any products other than FF and MDN. If private donations won't cut it and sponsorships tarnish their standing, what's left?