I remember Obama's AG admitting they were too big to prosecute after he left office. Something like it would undermine the confidence of the markets. It probably would have for a short time rattled the markets.
There are 3 other episodes of Frontline that are good to watch as well:
Inside The Meltdown (2/2009)
Breaking The Bank (6/2009)
Money Power & Wall Street (4 Episodes) (4/2012)