I think you are misunderstanding diddly. He is not saying that no one will ever mine the moon or asteroids, he is saying that it will not, in the foreseeable future, be done commercially, that is making a profit out of it. I agree that any talk of this venture happening now is, as he says, a marketing vehicle, and I also agree it won't be commercially viable for a long time, I just happen to disagree with the conclusion that it's completely unforeseeable that space mining will ever be economically on par with mining in extreme situation on Earth, although I don't think it will happen for decades.