Forgiveness is wonderful, but forgetfulness has no place in policy debates. The idea that the Moody's and Standard and Poors should be seen as impartial arbiters of the creditworthiness of the U.S. government, whose integrity and judgement is beyond question, does not pass the laugh test.
Their warnings over possible debt downgrades associated with delays in raising the debt ceiling may be made in good faith. Certainly the failure to raise the ceiling by August 2 would be very bad news for the creditworthiness of U.S. debt. But, their recent history suggests that any statement from these companies must be viewed with a bit of skepticism.
It is also worth noting that the markets have often not agreed with the rating agencies' assessments. Both have downgraded Japan's debt, yet the country can still sell 10-year bonds at interest rates of less than 1.5 percent.