The platforms for the most part really aren't "news" imo... they are basically tools for big content generators (ie. In the news space, local and national news outlets, journalists, etc.) to more broadly disseminate their message, and for non-content generators, they are a big news aggregator. Not unlike Facebook or Reddit or other sites, just in a different format.
The question then becomes, should these platforms have any discretion in what is disseminated on their platform. Seems like the answer should be yes.