(Note: this is an analogous thought-experiment, not how I really feel or think, obviously)
I must admit, initially my eyes jumped straight to the italicized text, and for a moment there I flinched.

But okay, I'll submit my mind as guinea pig for this thought experiment.
Eddy, I want you to stop posting in this thread. If you don't, I'm going to find you and use extreme violence on you. I'm a very volatile person, I'm quick to anger, and I usually get violent when I'm angry. If you post again on this thread, I won't be responsible for my actions because I simply won't be able to control myself. I've given you fair warning, so you'll only have yourself to blame if you get hurt.
So what are you going to do?
A: Push my buttons by posting again, or
B: Abandon your constitutional right to free speech and walk away, as I've told you to do?
Well, I think there are many variables to this, it's not so black and white.
For instance, I'd have to see evidence that you've inflicted violence on others in the past, I could do this by PMing other "neutral" users that have been on the site for as long as you (or have a similar post count). If the replies were along the lines of "No, he's full of it" then I would probably post again, no qualms. So in this case option A.
If the replies were "Yeah, look out for that nutter!" then I'd want to know if your violent tendencies were always directed solely at the instigator (in this case, the instigation being if I were to reply to the above "threats") lets call that scenario 1,
or, if you tended to go on a rampage, and started hacking and slaying innocent bystanders on your way through to me (maybe because they're called Eddy, or have a similar writing style etc, or maybe just because they are there) that being scenario 2.
Scenario 1: Straight away the school boy in me would want to say "bring it on punk!" (I too suffer from the human condition) but a few deep breaths and I'd hope to have calmed myself. However if the thread was about something I was passionate about, and vital to my place in the universe then I'd probably go with option A; I think it's important to defend your place in the universe. So then I'd start preparing to physically defend myself, remember in this scenario it's only you and I about to go to blows. (On a side note, do you think the burning of the Koran at the 9/11 event was
offence or
defence?)
Scenario 2: Well I'd seriously consider walking away, feeling the bigger man because of it (obviously reporting you to the mods and police is a given). I would despise myself if I became directly/indirectly responsible for the serious harm/death of innocent people (this is inherent to my stance in the universe). So in this case option B. But by choosing option B, I've opened up a whole other set of options:
1) Applying my right to freedom of speech, I could start a new thread entirely, being any one of a myriad of topics, but in this case probably one about the benefits of peaceful negotiation, and I'd just hope you'd read it, and get it.
2) I could PM you directly, (there is no set of instructions in the above threat that says anything about PMing you) and try to resolve it that way. The pride part of me would want to avoid a grovelling apology, but if I had posted something that directly offended/threatened your stance in the universe, then hey if a grovelling apology is what it took to have an end result of "no harm done" then I may consider it (I stress the word
may).
I could no doubt think of more, but it's morning here, and my brain is still waking up.