Public places that are privately owned have been determined to be subject to the requirements of government to protect First Amendment rights. Such places have usually been malls or areas open to the public. Social media easily meets the test of being a “functional equivalent “ of a public forum that must respect freedom of speech. The argument that ownership is private doesn’t necessarily permit selective censorship.
Most of my life long conservative friends have only heard of free republic from me, while at the same time they learned about instances where the MSM colluded with liberals to hide or distort the facts on their own from YouTube videos. Without YouTube and Twitter, however bad they are, conservatives would be relegated to echo chambers.