Single Sex Education - a violation of rights?

Having taught in co-educational as well as single-sex schools I can see a lot of advantages in each.  Single sex education is not the answer for all students, but it can help to focus teaching, as well as focussing students.  Regardless, it seems incredible that a court is making a ruling, in this case preventing a middle school from offering single-sex lessons.  Surely commonsense should be recognised as part of the US Constitution.