AdNauseam is silently clicking ads. This directly costs Google money. Google happens to control the extension web store for their own browser. Removing it from the store really isn't that bad. Uninstalling it from existing browsers as malware? A little more malicious, but I would still consider it self defense.
There is even a method to install it directly[1] which AFAIK Google has not blocked.
Granted, if Google were not both running the browser and the ad network, these actions probably wouldn't have been taken. But the whole attitude that this is some sort of tyrannical thing is a little over the top.
1. https://github.com/dhowe/AdNauseam/wiki/Install-AdNauseam-on...
Sure, Google wants to make money on ads and they're under no obligation to let people use their infrastructure to undermine that goal. But likewise, the people who get fucked over by Google compromising the Chrome ecosystem to defend their ad income are under no obligation to be particularly enthusiastic about it.