That program was designed as an alternative to easing the stress test or increasing amortizations, both of which would have involved more borrowing and an easing of credit standards that would have aggravated already high levels of household debt.
The reason it hasn't been taken on is probably a combination of either lack of demand, because those people are already well enough supported and those who said they needed more and there was a crisis on our hands were not factual, or they had a view that house prices were going to go up and they didn't want to share it, as opposed to house prices going down and those motivations would change.