the Supreme Court certainly has not upheld compelled speech. And internet theories about private services as de facto public forums continue to be defeated in court (PragerU v Google being the most recent example).
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."
the Supreme Court certainly has not upheld compelled speech. And internet theories about private services as de facto public forums continue to be defeated in court (PragerU v Google being the most recent example).