I should point out that in either case, the manufacturer gets to say what's your fault even if it isn't true - at least without wasting a lot of time and resources to prove otherwise.
If they are signing contracts that don't let them service the equipment when they can't get a tech, and if the equipment is so fragile and complicated that you can't use it without fucking it up, then multiple people fucked up badly and at multiple points. And just to head it off, I don't want to hear any ignorant fiddle-faddle about "these are complicated devices" blah blah blah which is all over this thread. No they fucking are not. They are ovens. There is no fucking oven used for food rather than aerospace grade carbon fiber that needs more intelligence than you can get for two fiddy from aliexpress. It doesn't matter how many timers it has, how many fans it has to operate, how many zones it has, or how many energy sources it can run on, an oven is basic fucking shit compared to other systems on the ship that they can service. There is no excuse for the level of incompetence and/or malfeasance that created this situation and it is absolutely incomprehensible why anyone would want to invent one solely to juggle the balls of some corporation not even named in the article.
How can you possibly defend such an indefensible and most likely born of corruption type of decision with some completely irrelevant horseshit about the vendor can blame you for things? The military doesn't give one tenth of one fuck, it's not their money and they never pass an audit and congress just keeps giving them more, they can be told that because they worked on it when they needed to get some meals out that they will need an entire oven and they will shrug and sign the PO.