There isn't. But we don't need an answer, not yet. The justice system is a lazy evaluator. This case has an easy answer--they are Nazis. If someone sued, the ruling would be quick. If the next case is more complex, reality will illuminate the nuances.
Common law systems are complex. They're also de-centralised and empirical. You don't always need a standard ex ante. We have a cultural standard regarding genocide, its advocacy, and Nazis. Existing norms and laws suffice.
(Philosophically, your question is interesting. It's practically irrelevant, though, until a matching case threatens to arise.)
How many or how detailed must threats against others' wellbeing become before you consider them unacceptable?
We weren't talking about promoting genocide, but about threatening and committing violence. If you can't debate with integrity, I'm not interested.
You chose to answer a question that had been addressed to someone else, which you're welcome to do, but it doesn't give you ownership of the conversation as you seem to imagine.
I said "Threats of violence are already illegal.", to which you responded, "Strange, I haven't heard of anyone being arrested for promoting genocide yet".
> Impugning my integrity because the topic of conversation makes you uncomfortable seems like a you problem.
Ha! If I had any doubt about your integrity, I certainly don't now. Feel free to keep trolling, but you'll just be shouting into the void; I'm blocking this thread.
Meanwhile, the point this article is making is that (in practice, if not in law) the current answer to the question of who decides what to censor is "middle managers at network infrastructure companies, based on what their social media departments suspect might hurt their brand." If you think that's an acceptable answer, great, but I don't think you can go on thinking of yourself as a "slippery slope fanatic when it comes to free speech" in that case.