See also the recent Ninth Circuit Court of Appeals decision on whether or not free speech applies on a private platform (spoiler: it doesn't).
"Despite YouTube's ubiquity and its role as a public-facing platform, it remains a private forum, not a public forum subject to judicial scrutiny under the First Amendment," the court said."
"Despite YouTube's ubiquity and its role as a public-facing platform, it remains a private forum, not a public forum subject to judicial scrutiny under the First Amendment," the court said."
https://cdn.arstechnica.net/wp-content/uploads/2020/02/youtu...