I know the level of metabolites found was vanishingly small, but without some comparison data from the general population who also eat beef (and probably in greater quantities), I don't buy it--either from Lawson or from Wilson.
In order for USADA to have accepted the excuse from Wilson there MUST be some such data somewhere. If anybody has it, a link would be great.
I'm not sure that I understand your position. You've said that, without some comparison data from the general population who also eat beef, you don't buy Wilson's excuse, but you acknowledge that "[i]n order for USADA to have accepted the excuse from Wilson there MUST be some such data somewhere" (your emphasis). Are you merely saying that you won't accept Wilson's excuse until you personally see the data that "must" exist and USADA presumably relied upon? (I also would like to see such data, if they exist.)
I have somewhat mixed feelings about these cases. I believe I understand why WADA chooses not to set minimum threshold concentrations for many banned substances, but it gives rise to some quite plausible cases of positive doping tests resulting from inadvertent or unintentional ingestion in amounts that would have no discernable effect on performance (or, in at least one of the "contamination by kissing" cases, no discernable masking effect).
Having not eaten any meat in the last forty years, I'm probably a bit less sympathetic than I might otherwise be to athletes who claim that their positive tests were caused by inadvertently consuming contaminated meat. Still, those critics who simply claim that professional athletes should know enough about what they're putting into their bodies to avoid all positive tests are, I believe, basically just idiots.