Of course they should be fired, they have no idea what they're talking about. They downgraded the US's ability to pay debt, but when the market tanked what did everyone buy? US bonds. If it was really less safe, why did investors flee there? And remember, these are the same jackasses who rated the mortgage securities AAA+ up until they failed and everything crashed. That is the same rating that the US debt used to be.
Why would anyone believe anything these idiots say? Their track record sucks. It seems to me like they are just trying to manipulate the markets to get what they want.