I guarantee it was deliberate.
My ex-wife does QA/QC for a USDA food producer. Each and every serving goes through a metal detector prior to packaging and the packaging does not (or should not) contain or be constructed of any metal. So the only way metal shavings get into the product is due to malfeasance after inspection by QC/QA unless QC/QA is in on it.
Not that it makes it much better, but I'm going to assume gross negligence and incompetence until deliberate malice is proven.
What the story sounds like is that whoever is in charge of feeding the Guardsmen pushed out a hasty and poorly worded catering contract that got picked up by a company that couldn't actually fulfill it's end of the deal and is just trying to fake it. The company gets X dollars per meal delivered, but they don't have facilities or staff to actually serve X full meals correctly each meal time and supply chains for food service are already screwed up so their normal shortcut meals aren't available.
Once the Guard takes delivery of the meals, it counts as delivered, so they chance it, over and over again. Dump and stir from tin cans without checking to see if the can opener left metal shavings on the food, don't check meat temps because the next batch has to go in to the ovens, menus are probably next to non-existent and rarely followed because of supply problems and the pace of delivery.
It could be sabotage, or sabotage could be a part of the gross negligence and incompetence, but I'd bet if there were still actual investigate reporters out there, it wouldn't be too hard to get to the bottom of what is happening.
Whatever the subject there are always Freepers with inside knowledge !
The Army has destination inspections performed by veterinary food inspectors. It is their job to make sure the food is wholesome as it gets to the dining halls. There is a breakdown in the system somewhere for this to happen.