One was too not raise the debt ceiling and use SS and Medicare funds to pay off the debt;
The other was to default but just for a short while so as to provide more pressure on the Democrats. If we defaulted for say a month; it would hurt a minuscule fraction of the debt holders. If it actually would hurt debt holders China would be pointing nukes at us.
So the risk that a lender would not get his money back is incredibly small. As for inflating the money away. They could come to the conclusion that that would hurt the economy more then it is worth and default on all the debt collective (like of like declaring bankruptcy). This is a possibility in the distant future.