I see no reason why 1:many platforms shouldn't have the same protections as a 1:1 platform.
It is in the public interest to prohibit moderation by 1:1 common carriers. It is not in the public interest to prohibit moderation by '1:many common carriers'. But by virtue of being 'simple' carriers, they should both be free from liability for the content.
Note, however, I don't think it is very good to have these companies moderating themselves, but it's better than nothing at the moment. I'd propose legislating the scope of the moderation according to standards set by some internationally recognized ethics committee (not a government decreed scope, they are likely just as biased as a company).
Alternatively, platforms could offer something like a complex filter system that allows users to implement their own moderation policies. But this would increase the burden (costs) of the provider.
There are tons of protections, already in place, on large networks.