It's an exploit. It's a big bright advertisement that causes car accidents.
By official accounts, the Empire State Building was built in little over a year. Out of the five people that died during the construction, 2 died from falling. This guy's been climbing for 30 years.
He makes a living doing it, I'm sure. If I'm walking out of the ISD, and I see people looking up, I'm going to use the north side exit.