One of the big issues with the demonetization on YouTube is that it's a binary flag -- either "acceptable content for advertisers" or "unacceptable for advertisers." As if advertisers were a single block with a single set of values!
When YouTube is not under an obligation to act as the virtual-public-square (because "they're a private company"), then they are especially vulnerable to defining that "acceptability" either by internal ideological conformity, or by external ideological pressure. Part of the concept of "free speech" (as a doctrine, not just as 1A legal structure) is that it allows for a society where the distinction of "I don't agree with this but someone out there might and so it's OK for it to exist" is a distinction that is possible. Without that, we're left with a world in which expression has to be mediated by the approval/whims of external forces for it to be present.
Whatever strange, fringe things this person was having as YouTube videos, I'd be willing to guess there's some fringe company out there who wouldn't care if they were advertised on those videos. Think of the kinds of advertisers 4chan, Infowars, or adult websites get. Their standards don't fit into a generic mold of "acceptability." But if someone was a video creator who wanted to court such advertisers, what kind of audience would they even be able to build without access to the de-facto public-square that YouTube is?
I don't know how to get there from here. But I think a more healthy ad-revenue model would somehow have YouTube saying "OK, these mainstream videos are able to be monetized by mainstream ads from companies A B and C, while these fringe/controversial videos can be monetized by whatever companies X Y and Z want to."