My understanding is as follows. As a platform, the rationale for section 230 protections is that you are not the one making the comments, and are thus just a platform for the speech of others. The speaker, and not the platform, is thus the one liable for the speech. Conversely, a publisher, while not the one writing (contributors write, and the publisher publishes), still bears the brunt of the liability.
I thus think it is intuitive (to me at least), that after a degree of control is exercised, this flips into being more like a publisher than a platform, and should be treated as such. The question then becomes where to draw that line.
Before 230, there was already effectively a distinction in that, if you ran a forum and did absolutely no moderation, you were never liable for the content - but then you also couldn’t remove any content that was vulgar, racist, hateful to other users, etc. which is why section 230 is part of the “Communications Decency Act”. Without it, social media just choose between not moderating anything, and vetting every post (and probably only allowing posts from a small group of verified people and businesses).
LegalEagle has a good rundown: https://youtu.be/eUWIi-Ppe5k?t=4m18s
> that editorializing something such as [...] removing content or context
I suppose it would be permissible to draw a line where you could delete all or none of a users content, but not some, since that does sound content neutral. I don't believe anyone has drawn such a line though in law (and it would be quite the strange line to draw).