The demonetization policy is to serve their advertisers' priorities, not to promote the health of the ecosystem, and advertisers are unwilling to advertise against an enormous variety of content, including that put out by right wing, left wing and entirely mainstream commentators. It's also inconsistent precisely because it's reactive, defensive and not intended as debate moderation or any kind of evaluation of the actual merits of the argument.

And we're talking about an ecosystem for political opinion on a platform with low payouts here: the incentives are supposed to be convincing people of something you believe to be important, and thousands of politically active people are already prepared to donate time communicating with much smaller audiences than can be reached on YouTube. The health of political debate really doesn't depend on the representation of the sorts of opinions people are only willing to voice in return for a $5 CPM.