> no-one has ever confirmed they can actually be fired

that is untrue

In the case of nuclear arsenals that's perfectly fine - MAD simply needs to be plausible, not robustly demonstrated. In the case of CAs I'd argue that the description doesn't really fit since they're getting stress tested by malicious parties on a daily basis. By that logic you could describe linux kernel security as a potemkin village due to the steady stream of zero days. In reality a potemkin village is something intended from the start to deceive everyone else. It's not impossible that's what happened here but that's a very serious allegation to make (ie theorizing that the weak keys were intentional with a conspiracy afoot).