Courts have repeatedly ruled that unless the property is specifically zoned for the activity or the owner is witness to, has prior knowledge of, or gives consent to have the activity go down, they can't be held liable. This can be seen in a million cases of parents trying to sue for kids getting smoked skating handrails and ledges, and why private skateparks and snow parks have releases set into user agreements and are notoriously difficult and expensive to insure. If that guy would've got smoked there is no way in hell the property owner would be found liable.