Pruneyard Shopping Center v. Robins, 447 U.S. 74 (1980):
This holding was possible because California's constitution contains an affirmative right of free speech which has been liberally construed by the Supreme Court of California, while the federal constitution's First Amendment contains only a negative command to Congress to not abridge the freedom of speech. This distinction was significant because the U.S. Supreme Court had already held that under the federal First Amendment, there was no implied right of free speech within a private shopping center.[3] The Pruneyard case, therefore, raised the question of whether an implied right of free speech could arise under a state constitution without conflicting with the federal Constitution. In answering yes to that question, the Court rejected the shopping center's argument that California's broader free speech right amounted to a "taking" of the shopping center under federal constitutional law.And Facebook and Google are headquartered in California.
There was also a 1946 case from Alabama in which a company town tried to bar protestors and was prevented from doing so by the courts under similar logic ie “town square”.
There’s a good case to be made that Amazon, Google/Youtube, Facebook and Twitter are monopolies (it’d be a much tougher case to argue that against Apple). The “town square” rationale is another. Net Neutrality and the reasoning behind it is another rational basis for introducing regulation that would prevent censoring any but clearly illegal speech like kiddie porn, terrorism or making terroristic threats.
We cannot allow a few tech giants to come to utterly dominate the internet - like the do now - gaining their current size with a relatively free libertarian ethos and then once they’ve gained dominance impose draconian Leftist censorship. That would be very harmful to democracy and free speech. These have essentially become media companies rather than mere conduits which had no editorial oversight and therefore need to be regulated as such.
When that firearms company in Montana(?) was going to produce "for use in Montana only" then the feds claimed jurisdiction saying that the components had crossed state lines giving them jurisdiction via commerce. I doubt those servers were sourced and built entirely in California.
Also... A local girl (15?) took a picture of herself naked and sent it out to her boyfriend. They broke up shortly thereafter. He sent the picture to everyone in his contacts as fid his friends. A bunch of adults became recipients and someone reported it qs child porn. The FBI showed up claiming jurisdiction because "once its on the internet it has crossed state lines." These internet services are of course WW so they have certainly "crossed state lines" again making this, if we are to be consistent, a federal issue.
The USSC is almost going to have to reconsider "commerce" and other issues that make things federal or they are going to have to overrule California.