I think there is a difference between your post 28 example and the current example. In your example of criticizing the isolationism, the criticism is that the policy enabled the terrorism. In the current example, the claim is that the "interventionism" caused the terrorism. The former doesn't attempt to shift blame away from the terrorists. It was still their choice to act on their irrationality. The moral fault is still theirs for the action. The only blame being assigned to the policy is for making it easier for them to act, either by actually not resisting them earlier, or by informing them that their will not be any consequences. Each is getting blame for their own actions/inactions. The terrorist gets full blame for murdering. The government gets blame for not doing enough to prevent it. But there's no excusing the terrorist. There's no argument that he wasn't responsible for his actions, or was just "reacting" to stimulus.
Contrast that to the latter claim that "interventionism" caused the terrorism. The terrorists moral fault is spread around. They're said to be not wholly responsible for their actions, if they are at all. They are treated as if they are not moral agents, but mere animals who respond to stimulus. And instead of punishing them for their actions, the offered alternative is to stop provoking them.
Now back to your post 13. I still don't think you should take the blame for provoking the beating. So let me give yet another example.
There's a girl in high school that just broke up with her boyfriend, who was too possessive and mean. He's really upset about it. A different boy likes her. So he decides to flirt with her and ask her out. He knows about the ex-boyfriend, but figures he's not afraid of what the ex-boyfriend thinks, and he really likes this girl, and has for years. He takes his chances, and things work out. He goes out on a date, happy as can be. And then the ex-boyfriend shows up and attacks him, beating him to a pulp, screaming "She belongs to me!"
Now he could go and blame himself for the attack. His dating her was a "causal factor", after all. The point is that he didn't do anything wrong. The fact that the ex-boyfriend is psychotic and thinks his old girlfriend belongs to him was the problem. The new guy shouldn't blame himself, although he might anyway. It's natural to look back on a tragic event and ask what could we have done to prevent it. It's natural to want to imagine that you have control over such things in your life, and you could prevent them if you knew how. But if he had good friends, they'd tell him that it wasn't his fault, and that he has to stop blaming himself. They'd tell him that by blaming himself, he's increasing the attack on himself, and allowing the attacker to remain entirely free of consequences, even the simple consequence of moral blame.
As I briefly mentioned earlier, if there is absolutely no moral justification for the attack, it's really easy to see that it's the attacker that is at fault. But in your example, you felt like your insult was a proper motivation for some kind of response. You might believe that the beating was way too much of an overreaction, and so argue that it wasn't entirely justified, but it's easier to convince yourself that it was your own choices that led to it. You wouldn't have anyone who could convince you that you were entirely the victim here. So you'd take the moral responsibility for the violence as well. You'd say that the attacker was a mindless animal, and can't be expected to behave any better.
But I think this is a flawed thought process, brought on by the desire to feel more in control. I think you can accept that you shouldn't have said it, and that you did hurt their feelings, but that the blame you accept has to stop at that point. Taking the blame for the bullies excesses is just shifting of moral responsibility for his choices to yourself. The causal factor, your petty little insult, is not a justification for the attack, and shouldn't be consider one. It might be a justification for him saying something rude in return. But if you treat it as an open invitation to any kind of reaction, then you excuse any action on their part, for any reason. From that perspective, any action you take, no matter how innocent, can be seen as an "explanation" or justification for any response.
If your action didn't deserve a response, it doesn't matter to me whether it was entirely innocent, or if it was slightly rude. In both cases, it didn't justify that particular "response". The blame for that "response" is entirely on the attacker, because it really isn't a response at all, except maybe in the deluded mind of the attacker. But if that is the criteria for you to accept blame for his actions, then everything you do is a "causal factor". Your mere existence can be a "causal factor".