A newspaper has editors and a viewpoint. An online platform for folks to post their own articles does not. Its akin to the post office having an editorial board?
The post office is more analogous to the transport layer, in which case you'd be making a solid case for net neutrality, and I'd agree with you there. The post office having an editorial board would be like Comcast having an editorial board.
The “platform” excuse is dead on the first real legal challenge. It’s past time for these publishers to be held to the standards other publishers have been held to for decades or longer. They can’t cry “free speech” on one hand while acting like publishers on the other. When it was just galling hypocrisy fair enough, but they’re big enough and have supplanted enough “traditional media” that their time has come.