If you are profiting off someone's work without their permission, profitting people harming themselves or doing dangerous shit, profiting off illegal activity, or profitting off people's deaths, then by all means demonetize.
Demonetization is always "justified" for the simple fact that the infrastructure such monetization schemes exist as a part of are explicitly owned by private interests who have zero legal obligations to protect you or your bottom line while using their property. Such is the nature of private ownership.
Though remember, demonetization is a practice that exists at the behest of ADVERTISERS who don't want anything to do with you or your stated opinions tarnishing their brand name. The problem goes well beyond google/youtube and If youtube were a pooblek spess and youtubers had to deal with advertisers on their own terms your problems would be the same, having to appeal to advertisers who pay your bills because they didn't like what you had to say. Same shit different day, the world spins anew.
Fanartists making money by drawing copyrighted characters without permission is probably already something that could get you demonetized if Nintendo bothered to enforce their copyright