Answer: When he knows nothing about metals.
You just knew this Afghan mining thing about having one trillion (or is it three trillion?) dollars worth of minerals lying around would bring out the populist trolls, didn't you? And sure enough, head of the queue is The Great Pretender himself. Casey's Louis James writes the inevitable long-winded article that tries to make a serious point, but my absolute number one fave line in his FP note dated yesterday is this, while explaining why the $1Tn story is a crock:
"One does not have to be a geologist or an engineer to understand why."
"Louis James is senior metals analyst for Casey Research in Vancouver."
So if an unqualified, self-appointed spokesperson on metals gets to be "senior metals analyst" at the band of merry dudes known as Casey Research, may the Good Lord protect us from the junior metals analysts over there.