Views on collective responsibility for riots have changed a lot. These days, it's only the individual rioters who commit specific crimes that are thought of as bearing responsibility. But before the 1960s or so, a violent crowd was seen as collectively responsible, and it wouldn't have been considered unjustified to treat them accordingly, the way you'd be justified in violent self-defense against an individual rioter today.
I'm not saying they have to be 100% victims, but if you start off by violently assaulting people I'm not going to say that the people stopping you from doing so by force are in the wrong for doing so.
If you want to say a company was evil for sending armed goons to break up a group of armed goons assaulting people or destroying stuff, then you're just plain in the wrong.