I feel like I should come to the defense of mixed-gender schools here a bit, even though I realize your comment doesn't necessarily advocate gender isolation (but it does sort of imply the benefits of it).
I went to a mixed-sex high school, albeit you might choose to take this anecdote with a grain of salt since that was 20 years ago in Germany. There was certainly some bullying, although not on the scale I discovered much later in life was common elsewhere. There was almost no intra-school violence. I feel pretty confident in saying this because these things were taken very seriously by both staff and students alike, and the few cases where there had been confrontations between students quickly became very public and a matter of much water cooler talk afterwards. I can also say with about the same level of confidence as you that there was no rape, or other forms of gender-based violence. And coming back to the article's subject, CS class was mandatory for everyone at first - and even though in later years the course became one of those that could be voluntarily dropped, the gender balance stayed the same after that.
That said, school wasn't ideal for me as I was in it. CS class wasn't exactly great, mostly due to utter disinterest by 90% of the students who took it. At the time I had the feeling the school was a bad choice for individualists like me, though in hindsight I would revise that conclusion a bit (as a humanist-themed middle/high school it was actually much better than any other school I could have gone to).
I think it's important to bring young people up together and not artificially separate them into two groups. Of the many social problems present in my time studying there, gender issues were not one of them. There was no us-versus-them mentality, and informal social groups were almost always mixed. I can't help but wonder if that sort of normalcy is something single-gender schools actively campaign against.