Unless you and/or your friends have eaten the same pork (or beef) burrito from the same food truck, your personal experience at other restaurants or food trucks is irrelevant.
You think I'm spending time defending Shelby, but Shelby is just incidental. I'm being critical of a process with built-in shortcuts where the balance of justice has been heavily tipped against all accused athletes, that can railroad innocent athletes to full 4-year bans, when they don't know the source and/or cannot prove it with concrete and specific elements on the balance of probability (subjective assessment of some non-expert tribunal relying on expert witnesses to be both neutral and complete). Shelby would not be the first, nor the last victim of a process founded on the policies of "strict liability" and "guilty until proven innocent".
Such a process that does not separate robustly separate innocent athletes who cannot prove it from the guilty ones is bad for the sport, not only because it punishes innocent athletes, but because it hurts the reputation of the sport to an unnecessary degree by confirming to fans that the problem is far worse than what has been proven.
Anti-doping seems to be an important topic for many fans, but it is surprising to me to what extent it relies on bad science (to the extent it relies on science at all), bad law, and bad journalism, and even more surprising that so many fans are unable to see or accept how much they have been pre-biased to believe things which have never been proven to any standard.
I'm not saying the burrito excuse has been proven -- as it is a difficult proof for the athlete to provide -- but saying it has not been disproven or ruled out (because this is also a difficult proof to provide). Furthermore, it cannot be disproven by arguments about national distributions and probabilities (especially when these are based on unsupported or unproven assumptions). We need specific and concrete elements both to prove it and to disprove it, in this single specific instance.
WADA created this problem in 2015, by defining "intent" as something the athletes had to disprove. Before 2015, athletes were banned without any discussion of intent.
But I'm with you about stopping talking about burritos. What is the more likely alternative, and who has established that to any standard? Where can I find those arguments? In the CAS report, the bases of an "oral norsteroid precursor" is "suggestion", "consistent with", and "presumption". This doesn't seem like a very high quality argument from the pinnacle scientific experts and legal professionals in anti-doping. Many fans may be persuaded by it, because of the titles of the persons involved, but I remain skeptical of such weak arguments from experts who should be held to much higher standards (than the athletes).
Yet that is the current process -- Houlihan was railroaded to a full 4-year ban based on the strength of a suggestion propped up by presumptions, and many fans fell for it because they want to believe it is likely that distance athletes orally would ingest low amounts of nandrolone on purpose, and that ingestion of such low amounts would lead to national world records.