Edit: this turned into a really long comment, only the first part is an answer to the parent post. The second part is more of a personal philosophy of how minds work.
I'm far from an expert in law and/or it's interpretation. But I think that it's not too hard to see where the line is.
A single comment, or even a string of comments on a specific page does not constitute a "criminal" case of online harassment. Nor does a heated discussion in private over email or IM. However a continuous assault on your presence online, emails or comments on things you say or ED pages about you, do. That's just my opinion on these matters so if anyone disagrees maybe there is a case to be made for vague lines. However I think that in essence this is where everyone would draw the line.
More about human behavior in general, not specifically coupled to this thread/article. It's more like my personal philosophy of what human behavior should be like, as opposed to how it is:
It seems to me that it's in no way acceptable to voice your opinion in such a way that it is harmful to others, as there is simply no _real_ reason for it. I wonder sometimes why there's so much strife in all the circles of human society. If you really think about it, isn't it strange that we're only able to extend _real_ love to a very small circle of people around us (think family and friends)?.
I find it very difficult to articulate exactly how I think about human interactions with each other. In a very high-vantage overview I could try to summarize it like this, slowly building towards my idea beginning with how my brain seems to work:
The first idea is made up of two other ideas that I have: The 'human mind model' and 'compartmentalization'
First the mind model:
I've said this before on HM: The way my brain seems to work (and by extrapolation, maybe yours too) is that you have internal representations of the external world inside your head. When you see a plant, you don't see the _plant_, you could even say that you're not even _seeing_ anything. The photons that hit the receptors in your eyes somehow invoke the image of a plant inside your 'mind'. The things around you, the world that seems so coherent, is really only coherent inside your head. What you see, know, feel about a 'thing' is not what that thing really _is_. It's just the details and patterns your brain can parse and understand. I think there's information and knowledge about things that can't be expressed inside our brains. There's probably more information inside a spec of dust than can be encoded inside the brains of all the people on this earth.
Then compartmentalization:
To me it seems that the human mind deals with this problem by compartmentalizing everything you think about. If you're a mechanic you don't understand how an engine works. You have a very vague idea about the physics of combustion, and from there the idea of the combustion chamber in the cylinder 'emerges'. From your vague understanding of the interaction between a cylinder and an axle 'emerges' the idea of the engine. But this is not _the_ _engine_, just your idea of what an engine is. When you think of an engine you're not simultaneously thinking about combustion. Combustion is encapsulated in the idea of the cylinder. Just like the vague ideas and knowledge about 'interaction' are encapsulated in the total idea of an something that is solid and the principle of locality, which in turn are 'understood' by understanding space and time.
My takeaway from these two ideas is that there seems to be no end in what we could theoretically know and investigate. There's always something more and something deeper just like Douglas Hofstadter shows in the chapter of "Two-part Invention" in his book GEB.
My idea about human interaction follows from these two ideas. Like everything else, you don't interact with another human being. Instead you interact with the (flawed) _representation_ of that person in your head. And during the course of your life you build a 'generic template' of what a 'human' is. This is the representation you first begin interacting with when you meet a new person.
Unsurprisingly some people have a very bad 'default human' representation inside their mind-world, but really the fact alone that we need approach people through these mash-up jobs of a template seems bad enough. We all know how bad it is to be interacted with based on something that might not be true (super generic statement, meant to capture things like: judged because race, gender, etc, discrimination). But I can't seem to lose the idea that this is basically how we work, and that unless you put some real effort into it, you're predetermined to treat the most people you meet with a very unfitting generic template of 'humanness'. Because really getting to know a person the way our minds work takes time, and we simply don't seem to have that time to get to know everyone we meet.
I wonder if perhaps in the future we can change our brains to be more pleasant to each other by default, or more understanding.