Why would commodities crash? If anything, 18% on the short-end of the curve would cause a massive sell-off in the medium-long ends of the curve, and create absolutely massive losses for the foreigners who are invested in US debt.
If anything, those foreigners would be rushing like mad to buy commodities, not the other way around, simply to hedge and offset their bond losses, and in a realization that the US economy is not going to come back for a long, long time.