There is a lot of ignorance on this topic. People who favor of social media censorship of certain political persuasions claim that the first amendment only prohibits congress from abridging freedom of speech and that it does not apply to private companies like Twitter or Facebook or YouTube. Aside from the fact that the 14th amendment makes first amendment protections applicable to all levels of government, it also makes it applicable to corporations who allow the general public to use their property and who serve a public function. This is not just my personal opinion; although I wholeheartedly agree with the sentiment, it is the U.S. Supreme court ruling handed down in Marsh v. Alabama 326 U.S. 501
Many people in the United States live in company-owned towns. [n5] These people, just as residents of municipalities, are free citizens of their State and country. Just as all other citizens, they must make decisions which affect the welfare of community and nation. To act as good citizens, they must be informed. In order to enable them to be properly informed, their information must be uncensored. There is no more reason for depriving these people of the liberties guaranteed by the First and Fourteenth [p509] Amendments than there is for curtailing these freedoms with respect to any other citizen
In this case a Jehovah's Witness was convicted of trespassing for distributing religious literature in the town of Chickasaw, Alabama, which was privately owned by the Gulf Shipbuilding Corporation. Company policy prohibited solicitation of any kind, including the distribution of literature, on the privately owned streets and sidewalks. The Jehovah's witness was told she would not receive permission to proselytize and was asked to leave Chickasaw altogether. The Jehovah's witness protested this decision on first amendment grounds and was promptly arrested by a sheriff's deputy for criminal trespassing. The Supreme court eventually concurred in the Jehovah's witness's favor overturning the conviction and noting that the relevant distinction between where the first and fourteenth amendments are applicable and where the are not is not whether a place is owned by a government or private entity, but the function it is commonly used for.
The State (of Alabama) urges, in effect, that [p506] the corporation's right to control the inhabitants of Chickasaw is coextensive with the right of a homeowner to regulate the conduct of his guests. We cannot accept that contention. Ownership does not always mean absolute dominion. The more an owner, for his advantage, opens up his property for use by the public in general, the more do his rights become circumscribed by the statutory and constitutional rights of those who use it. Cf. Republic Aviation Corp. v. Labor Board, 324 U.S. 793, 798, 802, n. 8. Thus, the owners of privately held bridges, ferries, turnpikes and railroads may not operate them as freely as a farmer does his farm. Since these facilities are built and operated primarily to benefit the public, and since their operation is essentially a public function, it is subject to state regulation.
This aptly describes social media platforms like Facebook, Twitter, LinkedIn and YouTube. They are open for use by the general public, without charge, and function as forums for spreading ideas (both religious and secular), engaging in political discourse, and even advertising business the same way we used open public spaces such as side walks, parks and town squares in 1945. All of these large social media platforms are, in fact, public forums subject to first amendment protections. The fact that they are owned by 'private companies', a description which is a misnomer itself, is irrelevant. The entire argument that 'private companies' can do what they want rests on the mistaken belief that there is a single set of property rights protected by the non-existent legal doctrine of absolute property rights, which is found nowhere in the laws of any country, much less our own. Calling social media platforms 'private companies' is also a disingenuous red herring; they are public corporations charted by the states, in which they operate, for the purpose of providing a benefit to the public under their articles of incorporation. They are categorically different from proprietors, colloquially referred to as 'mom and pop shops' or simple fee owners of real property; comparing the two not only makes you a moron, but a belligerent moron to boot.