The context at the time was doubt that the treasury would pay its debts, because it was widely viewed that it would not post the civil war. The language is not clear, but the intent as I understand it from a historical perspective is pretty well understood to mean the treasury must always pay its debts. The language continues to clearly delineate debts accrued by the confederacy (insurrection) as NOT payable, which further enforces the topic is payment of debt.