But now that you have conceded this trite and mundane, but quite obvious, fact, the implications are that Houlihan simply failed to collect the evidence necessary to meet the "balance of probability" (50%) burden to prove "not intentional". I'm not convinced such a burden is possible, without a sample to test.
If, for emotional and non-intellectual reasons, you want to use other verbs that the CAS didn't use, like "reject" and "rule out", then the similarity and consistency requires you to realize that USADA, the AAA Panel, the subsequent CAS Panel, and a WADA investigation, all similarly "rejected" and "ruled out" any allegation that NOP athletes ever doped for the same reason -- even moreso as all four anti-doping/adjudication bodies gave an explicit statement to that effect, after, in addition to the normal course of anti-doping testing, having reviewed the evidence from 30 witnesses, a wide range of evidence including eye-witness proof, testimonies, contemporaneous emails, and patient records, more than 2,000 exhibits, and 5,780 pages of transcripts.