The Bill of Rights only covers negative rights: what Congress is explicitly forbidden from doing. Free Speech is a social norm as well as a legal construct; there are components of a civil society and Enlightenment values that have nothing to do with laws on the books: https://en.wikipedia.org/wiki/Principle_of_charity
Even if one concedes that any given platform has total authority over their private property (there is a case for regulating tech giants as utilities), one is still perfectly within their rights to vehemently disagree with those decisions, or find them to be grossly counter-productive.
Even if one concedes that any given platform has total authority over their private property (there is a case for regulating tech giants as utilities), one is still perfectly within their rights to vehemently disagree with those decisions, or find them to be grossly counter-productive.