At some level these platforms are the public square and facilitate public discussion. In fact, Google has explicitly deprioritized public forum sites (e.g. PHPbb) in preference to forums like YouTube. Surely there is a difference between declining to host and distribute adult material and enforcing a preferred viewpoint on a current topic.

Sure, Google doesn't need to host anything they don't want to; make it all Nazi apologia if they thing it serves their shareholders. But doing so and silencing all other viewpoints in that particular medium is surely not a net benefit for society, independent of how it affects Google.