Sorry, I don't think your facts are facts, and/or relevant.
A) The claim the the AIU was "pig offal" and the CAS told us the claim was "the 19-NA entered her body by eating a burrito from a food truck containing pork offal".
B) That doesn't seem relevant at all. It doesn't need to be maintained over a period of time, but only up to about the time of slaughter.
If you want to argue that the Mexicans were sneaky, that's between you and you. I don't blame the food truck owners, who seem to have responded to the best of their ability with answers to the questions and the receipts they could find. I can only go by what the CAS reported. The "expert witnesses" failed to discuss expected nandrolone concentration from the "fat" in a greasy burrito, except to concede it can contain higher concentrations of nandrolone, and failed to discuss "chorizo" at all, which may also contain various offal. This alone proves their rebuttal analysis is incomplete, regardless of the existence of any ingredient list. That leaves reasonable doubt.
Regarding vitamins, she didn't have all the vitamins from the sam batch. That again leaves reasonable doubt.
Before these questions are resolved, we can only conclude that it would be premature to exclude nandrolone from pork, as well as vitamins/supplements.