Free speech gives people in the US the right to say whatever they want. The government cannot lock you up for saying things the government does not approve of, as in Russia right now with the opposition leader they just locked up - the name escapes me now, or in China and now Hong Kong.
These kinds of things, in theory, should never happen in the US.
However, the right to free speech does not mean that newspapers, radio, TV, internet platforms have to publish what you are saying.
Facebook, Twitter, etc, can ban anyone and anything they want because they are a private business and not the government.
Many people do not understand this.
I also will add that the problem goes way beyond expression of "opinions." "Alternate facts" (Bless you, Kelly Anne Conway) are just plain old lies and that needs to be said.
_________________
The river is the melody
And sky is the refrain - Gordon Lightfoot