IRGC, Hamas, Hizballah and maybe others are far right organizations, so I don't think this is purely left/right.

And what about signal? I am pretty sure many violent/terrorist groups use it too.

I don't have an opinion about this group, because I didn't even know it existed. But, like often with things related to the free speech, I think this topic is more complex than you make it out to be.

Substack knowingly and openly platforms neo-nazis, allowing them to profit from their rhetoric while taking a piece of the action. Even if the authors avoid specific calls to violence to skirt the ToS, it still gives them fertile ground for recruitment and funding of their activities.

By your definition, then, Substack should be labelled as a terrorist organization and shutdown, yes?

I don’t disagree. I just don’t know if they actually were courting bad guys or bad guys used an encrypted services provider. Both? Neither?

And I don’t see anyone hand wringing about that list of bad guys. Calling some of them “left” is pretty ridiculous in the first place.

That part sounds a little like telling on oneself.

By that logic, you should stop paying taxes if you don't want to support terrorism.

so let's shut down the US government?

The traitors in power in the U.S. use signal and no one cheers for signal to be shut down