While the set is certainly unexpected, I'm sorry to say that this strategy wouldn't work very well in the competitive field. Here are some reasons why:
*Even with a defense boosting nature, Talonflame will still lose half of its health to Stealth Rock.
*Talonflame's typing and stats just aren't good for this type of strategy.
*Talonflame is meant to be a glass cannon, not a tank.
There are plenty of Pokemon who can deplete PP in a better fashion than Talonflame would. For example, Dusknoir:
Nature: Impish (+Special Defense -Special Attack)
EVs: 252 HP, 126 Defense, 126 Special Defense
Shadow Sneak/Ice Punch