Rittenhouse's right of self defense was compromised by him committing a felony (illegal possession of a firearm) when the homicide occured.
I think that count was a misdemeanor only, it was dismissed by the judge, and would not affect the self defense claim anyway.
Also, at least one person believed Rittenhouse had pointed an AR-15 at him, and when accused of having done it Rittenhouse said "Yes, I did." That's brandishing, and it's also a felony. Rittenhouse could still use self-defense as the justification for pleading innocent to a charge of murder but it's not an airtight defense due to his own criminal actions.
I don't remember that there was a specific person, but I remember that the ADA tried to claim that based on a few generously interpreted pixels on a still from a video taken from some distance. In any case, alleged "brandishing" was not demonstrated in court, and should not be used to dismiss or erode his self-defense claims.
I have never excused Rosenbaum for his actions that night. I have consistently noted that he was being very aggressive and that Rittenhouse was afraid of him. We can't be certain he was trying to disarm Rittenhouse but we can be very confident Rittenhouse was panicking when Rosenbaum chased him and caught up to him.
And rightly so. Rosenbaum was a genuine threat, and a "reasonable person" would feel a clear threat to life and limb in that situation. Hence, self defense.
If Rittenhouse had been unarmed, not deliberately inserted himself into the situation, and had done nothing provocative, then his right to self defense would have been just as you say: perfectly clear and obvious. But that's not what happened.
If Rittenhouse had been unarmed, he would not have had the means to defend himself.
He did not "insert himself" into the situation any more than the rest of the people there.
And lastly, it has not been established that he had done anything that a "reasonable person" would find provocative. Of course, Rosenbaum was the polar opposite of a "reasonable person".
He had no legal right to be where he was (after curfew in a city in a state where he did not live)
He had a much legal right to be there as anybody else. More so, probably, given that he and his friends (incl. Dominick Black) were invited by the car lot owner.
Him having a residence in a different US state does not change anything, and I hate that "he crossed state lines" has become such a trope by the left re this case. He lived 20 miles away, and had connections to Kenosha. Grosskreutz afaik had no connections to Kenosha, and drove from farther away, but I never see Leftists saying that he should not have been there.
Hell, AOC (when she was still Barmaid Sandy, hi Swammi!) drove more than 1600 miles in an oil burning Subaru and crossed several state lines to protest against oil in North Dakota. In America, we can move freely between states, and we do not have to have a good reason, or any reason at all.
doing what he was doing (illegally carrying a long gun and attempting to exert an authority he did not have)
The gun charge was dismissed due to a loophole in WI law, so you can't keep saying "illegally". And I don't know he attempted to exert any particular authority - do you have any evidence to that?
and may have provoked Rosenbaum by pointing a weapon at him, or at least seeming to have done it, and saying he had.
We do not and should not dismiss self-defense claims based on what "may have" happened.
That does not mean Rittenhouse is evil, or guilty of the most heinous crimes, or any of the other extremist bullshit people may be thinking.
At least you disagree with your ideological brethren on that.
There are degrees of responsibility and proportionality to consider. The fact Rittenhouse was still a minor while Rosenbaum was an adult is a very big factor, or at least is should be, which is yet another reason why the comparison to Trayvon Martin and George Zimmerman is apt.
I still don't see any similarities other than those two people were the same age.