Imagine what would happen today.
The boys were indeed "crestfallen", according to the article, and likely the authorities deemed that to be punishment enough. Next time these boys commandeer a plane, they will be more careful not to ditch it.
I practice Juvenile delinquency defense, and I can tell you that these boys would be placed in secure detention (Juvenile jail) and it would take some serious arm-twising to get them released.
It's a different world. When I was in junior high school back in the early 1970s, it was common for a half dozen of us boys to walk through the neighborhood to the abandoned gravel plant with our BB guns and pellet guns and shoot up whatever we found: bottles, cans, birds.... Just not each other. Then we would walk back through the neighborhood and go play basketball.
Can you imagine what would happen today if six kids with BB guns and pellet guns were seen walking through a suburban neighborhood?
My dad had a .22 single shot bolt action rifle with a box of .22 shorts in the kitchen; we were under standing orders to shoot chipmunks on sight, and we did. He hated the little bastards. Again, you can't do that today.