Aluminum is actually one of the most recyclable things we have. To the point where it's better, environmentally, to have single use aluminum cups that get recycled every time.
To be fair, I feel like that's kind of what the artist was hoping for. Would you be reading about his piece if some Philistine with no concept of what constitutes art hadn't thrown it away?
There was another story like this. The exhibit depicts an after party scene with champagne bottles and other party "trash" everywhere. It was placed in a room. The custodians thought there was a party earlier and promptly cleaned the room.