Earlier quoted context omitted.
The distinction the court is drawing isn’t about corporations versus non-corporations, but speech versus moderation. You say moderation is about “editorial control” but that’s exactly the debate. Is Facebook moderation equivalent to the NYT deciding what to publish and not publish? When someone reads a Facebook post, does anyone think that Facebook is the speaker? That legal fiction is attractive for various reasons,…
Even if you subscribe to the viewpoint that Facebook is a "pipe" rather than the speaker, it seems hard to avoid the idea that Facebook's choice of which speech it is a pipe for constitutes free speech by Facebook. Nobody should be confused as to whether a newspaper is the author of letters to the editor, but it has a 1st amendment right to choose which letters to publish.
A better foundation for this seems to be property rights—it’s facebook’s pipes, and their business what they do with it.