That sounds like a big jump even beyond "they shouldn't be able to control what they publish." Are we now going to require Twitter actively promote everything too?
How many obligations would you impose on everyone else in service of this hypothetical listener who demands to be spoon fed all points of view in the world without effort? Is a library allowed to have a collection if they don't fully advertise it's breadth? Is a bookstore allowed to choose what to and to not put on their shelves? Am I allowed to tell you what I think without telling you how many possible other views there are? Any of those are just as "chilling" as "twitter.com" not having all the content that "elonsjet.com" or "jacobin.com" or "foxnews.com" would...
Twitter/FB/etc are HARDLY important enough, and way less powerful than past media, to start telling people they have to amplify what other people say.