The private business argument is weak as you're really pointing to the freedom that businesses employ. Quite obviously censorship runs contrary to the idea of freedom and the spirit of the law. Private industry does not have an inherent right to censorship, it is only legal currently because social media is a relatively new form of communication. This censorship has clearly been disruptive and since social media is essentially serving the role of a telecommunications provider those laws surrounding their freedoms are likely to change. You have to be careful because just because something is legal doesn't make it right. Social media companies can also read your private messages and share your private photos but that wouldn't make it right.