Geithner's rationale:

The Treasury Department defended its approach as a compromise that would avoid the dangers both of too gradualist an approach and of one in which taxpayers bear the entire risk.

“Simply hoping for banks to work legacy assets off over time risks prolonging a financial crisis, as in the case of the Japanese experience,” the department said. “But if the government acts alone in directly purchasing legacy assets, taxpayers will take on all the risk of such purchases along with the additional risk that taxpayers will overpay if government employees are setting the price for those assets.”

It seems sane to me. If it works.