Freedom of speech means to be free from government reprisal for speaking. It doesn’t mean you are free to say whatever you want whenever you want and it certainly doesn’t mean you are free from other private entities taking action based on your speech. ( see Duck Dynasty).
What the person that you quote says is true how things stand now. It’s clear that they don’t understand what Constitutional protects means or how it even relates. IOW’s , to use his example. If I decide that there’s no speech on my property on Tuesday as things stand now that is not against the law or a violation of anyone’s “freedom of speech. If there is no government, nothing changes in that regard. Except that there’s not a government to go back on its word of not sanctioning you for speaking out against it.