Normally the product would be stored in a refrigerated building supplied with electrical power. When the power went out, they had a couple of diesel generators as backup. When the generators went underwater, they moved the product to refrigerated trucks. At that point, I suspect that they had to decide whether it was safer to put the trucks on the road in the storm or leave them on site and hope they wouldn’t fail.
That makes more sense. The trailers were a last resort and not just leaving a trailers full of product behind.
Makes you wonder, if they are that important, why weren't the generators installed on a higher floor?