Maybe you missed the part in the original post that is now in bold. There were other islands where the kid could have done the skating, so why should he be allowed to ONLY do it at one with a car there, taking the chance of either sending his skateboard into the side of the car or getting his own head slammed into a mirror or something.
To my way of thinking, the kid was being disrespectful, rude, and dangerous. Suppose someone else had been in the car and decided to open a door as the kid came by. Would that have changed your thoughts of why the kid shouldn't be doing what he was doing?
I didn't miss anything. We can "suppose" and "what if" a hundred scenarios but until something actually happens he's just a kid riding a skateboard. Now "if" he was an adult and "if" he was open carrying then I would agree and call the authorities. Those freaks shouldn't be allowed near me, can you imagine if....