This looks like the sleeper point in Page's report at page iii of his Summary that may have ratcheted up Flaherty's hostility:
In fact, the budget officer insists there is even some wiggle room for the program. The report said "the federal government could reduce revenue, increase program spending or some combination of both by 0.4 per cent of GDP annually while maintaining fiscal sustainability. This amounts to $7 billion in 2011-12."$7 billion in present day budgeting flexibility would undercut the Conservatives' rationale for various austerity plans. Am no economist like our Prime Minister, but it sounds like a wrench was thrown into the Flaherty budget plans right there.
More on the fake OAS crisis: "There’s no old age security ‘crisis,’ PBO report shows."