It couldn’t just be that Cameron is trying to gin up ratings for his documentary that contains no proof, but lots of speculations. This is just like a UFO or Bigfoot search. Will it contain footage of people looking amazed, while not showing what they are amazed over?
Cameron is a complex individual. Check out his video documentary of his attempt to reach the deepest spot in the oceans, if you haven’t seen it. He seems to add a certain level of proof/credibility to his projects, IMO.