That's not a limitation on property rights. A farmer polluting the water supply is an example of the farmer damaging a shared resource that does not belong to him.
> Cloudflare to pollute public discourse by injecting the biases of its leaders into it.
This has nothing to do with "public discourse". CF is a privately owned business refusing to provide a service to a privately owned website. CF is not obligated to do business with them for any reason, and frankly, it's pretty reasonable for a company to want to have nothing to do with a website where domestic terrorism is regarded as funny at best and actually put into action at worst.
Direct threats to violence though will likely not be protected as it would stifle free speech. But, saying that some speech could "maybe" or "potentially" lead to violence down the line is usually not an argument against allowing it.
Besides, it should ideally be a democratically elected civil government who decides these matters, not for profit private companies and its leaders.