The misconception is that freedom of speech means anything other than freedom from prosecution by the state for your speech. It does not mean you are entitled to a platform, it does not mean you cannot be shouted down, and it does not mean private entities cannot (or even should not) censor your speech.

It's important to keep unpopular speech legally protected. It's not at all important to ensure it has a robust platform. For example, Nazis should not be arrested for saying Nazi things; but they should absolutely be deplatformed, socially shunned, and have a blind eye cast when they get punched in the mouth for saying Nazi things in public.

What about "The radical, left-wing Democrat president is continuing Antifa's crusade against Americans by forcing Cheerios to adopt the supposedly environmentally friendly policy of milking bats to produce the classic American breakfast cereal."

Where does that fall? It sounds like free speech to me.

Constitutional right to free speech does not equal a right to a platform for that speech.

Exactly. That's why communists don't have a voice anywhere. It's no one's fault that rich and/or politically powerful people more easily align with authoritarianism and fascism and just so happen to own those platforms. It does mean that groups and individuals advocating for under-represented perspective languish in obscurity. And there's no reason why those voices should be represented on any mainstream platform. They have a constitutional right to scream at the top of their fossil-fuel charred lungs about climate change on the corner of the street like any homeless person. They don't have the right to do it on Twitter or Facebook.