Something important to note here is that there are various exceptions to freedom of speech protections from various time periods, one such exception is Incitement – If a person has the intention of inciting the violations of laws that is imminent and likely, while directing this incitement at a person or groups of persons, their speech will not be protected under the First Amendment. This test was created by the Supreme Court in Brandenburg v. Ohio.
This is relevant because alongside the TikTok forced sale they also passed a law against sending sensitive data including personal details and photographs to adversarial nations including Russia, China, Iran, etc. That means that Incitement could be used to describe TikTok operating in any capacity without completely centralizing to the USA, and therefor they would have no protections by the first amendment.