Earlier quoted context omitted.
This has nothing to do with the bill of rights. Agreed. You don't have an inalienable right to spread whatever political lie you want In the U.S., you do. "Real" media do it all the time. There are laws against making slanderous or libelous statements against individuals and entities, but every American has the right to say, "the moon landings were faked and greens are smarter than libertarians" if they want.
You dropped the most important part of that quote: "to millions of people." You're free to go on any street corner and rant about the moon landings. Facebook just isn't under any obligation to give you a platform to reach millions of people with that.
Typically, an individual lacks the reach to make statements visible to "millions" of Facebook feeds, unless they are celebrities.