"if she was willing, do you think it will be of any benefit to her to stand up in public and describe personal, intimate matters so that someone she likes can be harshly punished?"

Most emphatically yes, it will be of benefit to her to be directly involved in fighting against the shit-headed bastards who have attacked her and someone she likes. Yes, it will be of benefit to her to get up in court and be forced by assholes to tell them her personal business that's none of their business, so they can harshly punish someone she likes, against her clearly stated will. How can that possibly be of benefit to her?? Because I'm comparing it to the alternative, of doing not a damned thing to fight against the injustice, to stand by silently and let the bastards punish him just as harshly, without doing anything to try to help him. And more importantly than that, it would benefit her, as a role model, to let her see an adult she likes standing up for what he believes is right, against people who are wrong. And it will be of benefit to her in the same way that any fight against any injustice would benefit her. It will also benefit her by showing her exactly who is doing the harm, and who her anger should be directed at, when she sees for herself what they do. The alternative is to 'spare her' the harm that others would do to her by invading her privacy in this present case, and let her be harmed by those same people over and over and over for the rest of her life in the same way they're harming him now.

(This is, of course, only in the case where he's innocent, having done nothing with her against her will.)