If peanut butter is edible, are the inedible, reference peanut butters stored in NIST, degraded due to aging, really a good peanut butter to reference with? Who knows what's the contents of them, and whether or not they represent the peanut butter we're familiar with.

(Arguments in blockquote means that I’m paraphrasing someone else’s argument for demonstration purposes. It doesn’t say whether or not I agree with the argument, unless if it’s explicitly stated.)