According to a recent study from New York City up to half of all students with orthopedic injuries are refused attendance at school. Principals say there are safety concerns. They are afraid of the liability if the child falls or is injured further while at school.
The report cites overcrowding, rambunctious children, and narrow stairways as safety hazards for already injured students.
Your nephew’s activities as a skate boarder may have nothing to do with the school’s refusal to allow him back. If the school says it’s in the best interest of the child to stay home during recovery, then find out about home instruction. Each state has its own requirements and laws about this policy.