Jones tested clean in their first fight just like DC did. Even using CIR testing. So, do tests prove cheating or not? Jones haters want it both ways. They say he failed for turinabol so cheated in the second fight. At the same time he passed in the first fight yet people insist he must have cheated then too and has cheated his whole career.
There's nothing logically inconsistent about this position. Any diagnostic test will have sources of error that can result in a false negative or a false positive. If you're aiming for a very low false positive rate, which I'd assume you are with PEDs, to achieve that you're likely going to have to design a test with a high false negative rate (this is often mitigated by two-stage testing, in which something like T/E ratios constitute a screen). So, while failing a test may provide strong evidence of guilt, passing a test can simultaneously only be fairly weak evidence of innocence. But odds are cumulative, passing one test might be weak evidence of innocence while passing many might be strong evidence of innocence, generally.
As a result, when considering a single, individual fight, you might interpret a result differently depending on the rest of a fighter's results. When a fighter has no positive tests, you give him the benefit of the doubt in every fight. If a fighter has one positive test, you might eye those negatives with a lot more suspicion, given the high likelihood of false negatives. If a fighter has multiple positive tests, as Jones does, you'd be crazy to ever give him the benefit of the doubt.
Jones's and DC's suspicious T/E ratios in the first fight should be viewed differently, because one has two positive tests elsewhere in his career and the other has none. If you take the attitude that nobody ever gets the benefit of the doubt because you think the preponderance of evidence points to a doping epidemic, I won't criticize it—I certainly take that attitude in sports and promotions with weaker testing regimes. But you'd be crazy to ignore Jones's positive tests when you're determining how credible you find his negative tests to be.