Incitement to violence and genocide is already illegal and is excluded from First Amendment protections (ncac.org/news/when-can-speech-be-punish…), so that is not what is being debated here.

Individual businesses have the right to set their own policies regarding speech, which Substack has done along with empowering individuals to control their own experience through blocking and muting. This provides the protections you are advocating for without infringing on individuals’ rights to freedom of expression.

If you have any genuine examples of the planning of extremist violence on Substack, feel free to share those. If they violate the law regarding incitement of violence or genocide, then they would be banned per the existing legal framework.