It's not about sharia, it's about modesty. Girls have a right to cover themselves more if they want to. That's freedom, people.
Shorts ARE modest attire for athletics. So many freepers ride France all the time but at least the French said no to the Mohammadan fanatics on public school attire.
I remember when I was in Hillsboro HS in Nashville, the girls wore one piece short jump suits for gym. They said playing vollyball was bad in those outfits cause the one piece garment rode up when the hands were extended over the head causing CITC (Cloth In the Crack).