It's a poetic weekend

Triple A rating
Three days before a default
Makes sense to someone

In fairness, it's medium term (10-20yrs) debts that pose an economic problem for the US, so in normal times a AAA bond rating would be appropriate. Over the long run, AA+ is probably the most appropriate given the state of economic growth and "Alternative Fiscal Scenarios," but downgrading T-bills is almost as explosive as finding white, black, red and pale horses to ride through global financial capitals.