Component “shelf life” might be one of the more widely misunderstood topics in the industry.
The main question there is solderability: protracted exposure increases the amount of oxides/sulfides/schmoo that forms on the component terminals, potentially impeding the reliable formation of a solder bond.
But said schmoo begins forming immediately upon manufacture however, and is present on pretty much every component regardless of age; that’s why solder flux is a thing. The rate at which schmoo forms is affected by storage conditions, and the amount of schmoo buildup necessary to cause solder joint failure at some specified defect rate is affected by the solder process and materials used: all such things are outside the manufacturer’s knowledge or control.
Folks don’t like indeterminate answers of that sort and like accepting responsibility even less, so some manufacturers throw out a very conservative and conveniently-round number as a “shelf life” figure that’s likely to give acceptable solderability for most storage conditions short of a continuous saltwater mist… The problem with doing so is that it results in a lot of perfectly serviceable parts being wasted and creates a nasty logistics/supply chain issue.
if these parts can be re-baked and used
The blunt answer is that they’re your parts at this point: whether you choose to use them in the typical fashion, add them to your granola for extra texture, or mix them with legos and sprinkle them across the bedroom floor is completely and totally up to you. However, all responsibility for the results of those choices is also yours.
This post has some useful references.