Reporting someone when you're not the one directly effected


Hello forum, I have a question that’s been burning in me for a long while now. How do you report someone when the abusive behavior they are showing is not directly effecting you? There is a user who is currently posting a private phone number of a woman, adamantly claiming the random woman whom she doesn’t know to be someone else. The random woman accidentally contacted the twitter user and now this user is posting snap shots of their text conversation on twitter without the random woman’s knowledge. This user has been suspended multiple times, and it seems like unless the abuse is directed towards ones self that nothing really happens to that person. How can the user be properly taken care of if people who know about the situation but are not directly effected tries to report them? What can one do in this situation, especially if they don’t know the random woman?