We agree that motion would be similar to releasing a ball that you are spinning in a circle by rope. When released, it continues with the instantaneous tangential velocity at that moment. However, the skateboarder's center of mass (lower torso) is somewhere on the order of 2.5 to 3 feet away from the ramp surface. Fundamentally his circular path of motion is offset from the ramp surface. Over course of his free motion from release to re-contact, he's only in the air long enough for his center of mass to get closer to the wall by like 3ish inches. Therefore, he can clear the ladder and quickly get back to the board before hitting the ramp wall.