I have a hunch that the team on this account are double agents working covert for the other 3 Aussie banks on a mission to systematically destroy the CommBank brand.
I can't embed the ad 'Bomb Hoax', it's now been removed from YouTube, but it can still be viewed over on Campaign Brief.
Suffice to say it's the latest instalment of a campaign that just when you thought it had hit its dumbest point, it keeps on getting dumber.
From a psychology point of view one can only summise that this is a classic case of 'sunk cost fallacy' or 'escalation of commitment bias'.
This is the phenomenon whereby people or an organisation will justify increased investment in something, based on the cumulative prior investment and despite evidence clearly suggesting that the cost of continuing the decision now outweighs any anticipated benefit.