If Google was compelled to keep arbitrary content monetized, the first thing they'd do is improve the tooling for advertisers to opt out of objectionable content in a more automated way.
You're just pushing the problem to a different level. It's easy to make a case that Google has to carry content, but forcing advertisers to spend money sponsoring it?
Yes but I'm pushing the problem to a level where there is competition. There are many advertisers. If even a large group of advertisers doesn't want to advertise on Russell Brand's videos, fine. Probably he would get significantly lower ad rates than other more widely acceptable content, but that's between him and the advertisers -- there's no middleman that refuses to let him make any money at all.
Frankly, I think supporting content through advertising stinks, but that's another matter.
You're just pushing the problem to a different level. It's easy to make a case that Google has to carry content, but forcing advertisers to spend money sponsoring it?