For so long social media companies have been disguising themselves as a method of free speech to hide their true corporate nature. This is why they have avoided censoring @realDonaldTrump and others.
Social Media companies want us to see twitter/Facebook/Reddit/Instagram like a public-use bulletin board when they are really more analogous to the Target intercom system. This keeps the users from realizing they are generating content for corporations for free.
But, most importantly, when social media corporations disguise themselves as public-use bulletin boards they confuse the public into thinking first amendment protections should apply to user-generated content AND THEREFORE we should not regulate social media as a whole.
Plainly, twitter (et al) wants to be seen more like your right to self-publish a manifesto and less like a corporation for whom we work for zero wages while they steal our data. They are hiding behind the Bill of Rights which, simply, does not apply to them whatsoever.
As a result, users like @realDonaldTrump are allowed free range to “say whatever they want” in “the name of free speech.” That right is not guaranteed by the BOR, but rather, it is promised by the terms and conditions of this corporate entity.