The legal system provides the mechanism to address that specific category of speech.

“Defamation is an area of law that provides a civil remedy when someone's words end up causing harm to your reputation or your livelihood. Libel is a written or published defamatory statement, while slander is defamation that is spoken by the defendant.”

If you want free speech you need to learn to live with free speech. That means not believing everything you see, critically thinking, and actually vetting the sources yourself. Its a societal process that plays out over time. The answer is not to have content oligarchs that decide what is truth and can be seen. Statements like this eventually are just seen as noise and ignored as people look for verifiable truth via trusted sources within platforms. In short, it works itself out.