>It seems incredibly unlikely that there wasn't some sort of verbal provocation from Rittenhouse's side.
At that time tempers were already flaring nationwide and I find both the above, as well as it's inverse, plausible. Most likely, both sides were clashing, as is oft the case in situations as volatile as this.
Returning to the NYT's video of Rosenbaum, there's a few things to note. One, that he was potentially mentally ill (relevant?), and two, he was directly antagonizing the "militia", sufficiently so that the other protestors felt it necessary to stop him [1].
In the later part, of the same video (note that there's a cut though), Rosenbaum seemingly suddenly pursues[2] and continues chasing. Only after he gets quite close (in my opinion; 18:04 or so), do we hear the first shots. There could be a hypothetical in between to fill in the gap, but given the available evidence that I'd observed, I gave more credence to Rosenbaum ultimately initiating.
>To be honest, I think things started to go wrong a lot earlier than that though. ...
So, I think that while I'd agree with you that yes, the problem started long before the first shot, I would think that it's better to evaluate it at point of firing. Otherwise we'd be chasing this rabbit hole till the end of time.
The protestors and rioters shouldn't have been there earlier as curfews were in place, and the police should have been enforcing law. The side arguments of open carry vs gun ownership and the inherent lethality increase a gun brings to any conflict, all the way to "gun rights". These arguments however are all applicable to the situation but are far more general, and I feel, a too tempting distraction.
I thus divide these into two different questions (or more, if necessary) so they can be addressed piecemeal. 1: At the time of firing, was Rittenhouse justified. 2: All the other bits and bobs about the context of the situation and who should have been there.
For the first, I've continued to make my case above, while for the second (rest?), this comment is long enough as it is, and I'll leave it open for now if you want to pick that one up.
><On facebook's topic ban>
This one is a bit more dear an issue to me, being a question of speech rights. But it's also one of those which I haven't come to anything solid. However, picturing myself in that situation, I'd be aghast to have a whole pile of media flaming me and having whatever scant opposition to that narrative literally blocked.
EDIT:
Oops, I missed your line on Rittenhouse's belief in his immediate danger. I think we've already come to the same conclusion in a different thread in which the government, and it's dereliction of it's duty to maintain order is probably the one who should be most at fault (correct me if I've misplaced your position).
[1] https://youtu.be/VpTW2AJE9MQ?t=846
[2] https://youtu.be/VpTW2AJE9MQ?t=1056