He's defending his opinion and has no choice given his firm's take on things. However when Yergin uses arguments like (paraphrased) "at other times in history there have been those saying oil is running out... and each time it didn't. What makes this time different?", my reaction is:

• he has a point, but
  
• this time the oil industry, not regulators or watch dogs, seem to be ringing the alarm bells as loudly as anyone.

At any rate there are always two sides of any big argument. He'll be right or wrong.

But consider this: The world certainly will not be a worse-off place if Peak Oil is taken seriously, sooner than later, so no down side exists, in my mind, in contemplating this as a serious issue for all of humanity to face, whereas dismissing it as too-much chicken-little talk has the potential to be catastrophically dangerous to humanity.