If I remember correctly, it should be film. My friend is his second assistant and she once told me that he shoots all black and white photos on film and he only uses digital for colour. I can ask her to confirm if it was the case this time as she was assisting on that shoot. I'm sure he does still shoot tons of film because she often tells me how difficult is to keep up with his shooting while loading cameras.
Wow, now that really is inside information! I'd love to know what he was using!