There is a clear risk that the US will instead lump trillions of losses on foreign investors and attempt to protect the purchasing power of their voters. It isn't like they're fooling anyone either way - they borrowed a bunch and can't pay it back. They can pretend they paid it back but the markets are going to respond to the magnitude of the losses and not the excuses. The leadership may as well let the bulk of the damage fall on people who don't vote in US elections - there isn't any particular reason to do otherwise.
The US could choose to tank their own currency but it'd be more orderly and the incentives certainly could be aligned to formally default regardless.