Interesting, to be honest my thoughts are very mixed. On it's surface this sounds cool, but I am wondering if there was actually bullying involved, and of course if there was it occurs to me that this kind of intervention is awesome to read about but one also has to remember that what happens when all of the victim's cool friends aren't around anymore can't be predicted.
As some people have pointed out "Star Wars" isn't a boy's franchise exclusively. Star Wars has been popular with girls almost as long as it's been around with Princess Leia being iconic, and the prequels going out of their way to set up Amadala as an action girl... which helped along Natalie Portman's career and she's even been able to do movies subtly parodying her early role.
It sucks but it needs to be understood a school can only have so many "Alphas" and at a certain point you start seeing strong personalities bang into each other and of course when that happens only one of them winds up dominating. A lot has been written about this, shown in movies, talked about in songs, etc... it's part of human behavior. Typically you wind up seeing one pecking order develop among students up through Jr. High, and then a separate pecking order appear in High School which can be very different. The parents talk about their daughter being more withdrawn and "less herself" as the primary symptom, and that seems pretty typical of a strong personality that has simply wound up on the losing end. That doesn't mean someone is being bullied (though it can). My initial thought was that picking on "Star Wars" for being "boyish" was simply the competition looking for something that could get under her skin, and it worked. When the social order settles is when you have to worry, the people at the very bottom who have no friends and get pariah status are the ones who are generally bullied. If she has friends she might just being socially relegated to the invisible masses in the middle between the popular kids and the nerds at the bottom. Having a strong personality means one comes into conflict for the social Darwinism. School is a bloody shark tank... sociologists have had a field day studying the patterns year after year. It sucks, but the parents might just being overprotective. If the problem persists and it goes beyond the "Star Wars" stuff, the girl winds up with no friends, etc... that's when you need to worry and bullying becomes an issue.
I'm simply pointing this out (and probably not articulating it well) because of the whole non-sequitur some people have pointed out about Star Wars never having been boys only. I mean heck, even when I was a kid it was marketed very cross gender, and if a Chewbacca shirt is involved that's odd because Chewie has always been seen as "cute" and one of the iconic characters girls have always been attracted to even when traditionally "girly", and the same can be said about R2-D2. I don't know anything, I'm just making a guess because the situation seems a bit weird. It's possible the parents are overprotective and don't remember what school is like.
That said in this case it's going to be a self correcting problem I imagine, the new Star Wars movie is out in December is it not? Shortly thereafter a new wave of "Star Wars" mania will hit, and I can virtually guarantee every kid of both gender is going to be clamouring after the merch. She bides her time, and she can toss the irony right back at the people being critical when they all want similar kinds of stuff to what she already has. There is a certain power in school to being able to say you were into something "before it was cool", which she can do now since she was there ahead of any of them.