He wasn't actively shooting, dumbass.
Neither Huber nor Grosskreutz saw Kyle shoot Rosenbaum. And it isn't illegal to shoot someone in self-defense in the first place.
Those convicts were simply predators chasing down prey.
Rittenhouse shot them about 10:05 PM.. Why didn't he just go home? The protestors were going home before dark.

Timeline of alleged Wisconsin protest shooter's path
A timeline of the path of Kyle Rittenhouse, the alleged Wisconsin protest shooter, at Kenosha, reconstructed in video.