They don't see publicly debating for a month about defaulting on a loan for the first time and coming close to being within a day of doing it as anything that could possibly shake investor confidence? Isn't the AAA rating for ultra rock solid, and that dragged on public debate gives off the impression of anything but ultra rock solidness.
The US did not come within one day of defaulting. It came within a day of hitting the debt ceiling, which is a very different thing. Despite the way it was portrayed, the government could have limped along for days our weeks without defaulting.
(I'm not saying that would have been a good thing--just that the idea of August 2nd as the day default would have occurred is incorrect.)