[how is it free speech if "russia today" is banned by youtube or facebook or twitter]

Here's the thing about free speech in America that people miss in these arguments. The U.S. government can neither compel nor deny your right to say or platform your speech as long as it isn't a call to act as a threat of violence or hate speech. YouTube, Facebook and Twitter are private companies and don't need to platform anyone they don't want to, technically. They might be sued for discrimination, I guess, but not for infringement on your right to free speech. They aren't viewed as a "public square", as they aren't funded by the government.