Earlier quoted context omitted.
An American can exercise their government-protected right to free speech on their own website. This right does not apply to someone else's website, since it would be infringing on the website owner's property rights. Freedom of speech doesn't grant the speaker the right to occupy someone else's private property.
If those websites wish to police speech to this degree then they can reclassify themselves as publishers and accept all the legal burdens that come with it. At least then they'd be intellectually honest.
The "Facebook © 2019" notice on each Facebook page tells users that they are on someone else's website. Next to the notice is a link to Facebook's terms of service, which discloses their "Community Standards". Facebook has been dishonest in many situations, but they don't hide their ability to moderate content in any way.
It's certainly within one's right to be upset with Facebook's policies. If you feel strongly enough about this, you have the option to stop using Facebook, and you can switch to a different platform with policies that align more closely with your views. You can also publish your own website, where you can establish your own rules.
But Facebook's website is not your property, so you can't graft your preferred rules onto Facebook. You can ask them nicely and you can apply social pressure, but Facebook makes the final decision on how they run themselves because the site is not yours.