they burned it due to the incredible size of the cash, easier than transporting it to the US.
They also did this when i was in Columbia, when a drug lord was captured, (Escobar) and they found a "Warehouse" full of cash. The amount was staggering...Just cant imagine a warehouse full of cash, but there it was...mind blowing.
Not to mention his mansions as well full of cash, it was everywhere, cabinets, under the stairs, in the walls even the Treasury guys said it was almost to the point of ridiculous....