It helps establish the credability of multiple witness statements that Rosenbaum was making death threats that night and incredibly aggressive even prior to encountering Rittenhouse. I established the victims weren't exactly heroic and didn't realize how much backlash that was going to create.

https://en.wikipedia.org/wiki/Kenosha_unrest_shooting

In the hours leading up to the shooting, prosecution witnesses described Rosenbaum as "hyperaggressive and acting out in a violent manner"[64] and "acting very belligerently".[65]

Witnesses described Rosenbaum carrying around a chain,[66] trying to light fires,[64] throwing rocks,[64] and trying to provoke fights with people by "false stepping" at them.[65] One witness described Rosenbaum "very bluntly asking people to shoot him"[65] saying "shoot me, n-, shoot me", using a racial epithet to which other protesters displayed "negative" reactions.[67]

Another witness described how, accompanied by Rittenhouse, he tried to calm a disagreement between Rosenbaum and another man when Rosenbaum made threats to kill both of them, saying "if I catch any of you guys alone tonight, I'm going to fucking kill you!".[64] The witness stated that he believed the threat was directed at both himself and Rittenhouse and that Rittenhouse had heard the threat.