Court entirely disagreed with your scenario, even the survivor admitted he was attacking.
The court was wrong. Anyone not blinded by ideology can see Rittenhouse crossed state lines to go cause trouble with a gun. His fig leaf of a cover blew apart and conservatives pretended it still applied.
Furthermore despite conservative judges protecting attackers this must be a tenet of self defense, otherwise there is no longer any way to convict someone of murder, except the arbitrary denial of self defense as an argument to defendants.
Nothing that happened after he grabbed a gun and went to the protest matters. If he hadn’t gone there with the intent of using his gun none of this would have happened. He is the instigating force and cannot claim self defense.