I have no problem with a witness calling the cops. However, if the victim is in shape to make a complaint about the crime and won't the cops aren't going to do anything about it.
Cops don't require specific people to make statements before they investigate a reported crime. The statements of the eyewitness who called them is enough. For example, if I see someone run you off the road and call the cops, they can investigate the crime I'm reporting regardless of whether you're suffering from short-term memory loss, or in shock, or fearful of further attacks by the assailants.
Maybe the cops in your town won't do anything unless you, the victim, file a criminal complaint. If so, you and your neighbors have my sympathy. Thugs must run rampant there.
If the victim can't report that's one thing, but that's not what happened here.