Re:A hand?
If it represents a hand, the central tower should be far lower, relative to the other towers "fingers". This would represent a welcome sign, like the pioneer 10 message.
If the second finger (majeur in french) is intentionally much higher, the message is of course one of hatred. Unfortunately, not one directed to the perpetrator alone, but to the entire rest of the world, friends and foes together. New York is a city with countless cultures, it's a melting pot of the entire modern world. Would they want to direct this message to their own brothers throughout the world?
Raoul