He said imagine, not "is this possible?"

I believe tom is giving us a thought exercise, isn't this what the forums are for.  Thinking up situations that could possibly happen, and what those consequences would be.

I for one think that the argument is a valid one.  As the price rises, the more miners jump on board.  The more miners, the difficulty increases.  Difficulty increases, miners want a price increase to cover it.  So on and so forth.  It all started about a month after the reward halving, and then when ASICs hit the scene then the price skyrocketed.

It's not an instant effect, but it's there.