Bad assumption.  I made Eagle Scout and I was a Scout Master for many years, and I know boys at that age.  Their has always been good reason for segregating boys in that environment as they focus much better....this is true in scouts, it is true in many private schools and it has been true in military basic training.  This has nothing to do with a girl defending herself...once the offense has been committed, the lawyers will come running for a quick settlement payday.