Charlie Francis spoke honestly and openly about Johnson's sabatoge. While his credibility was certainly dubious, his explanation was almost unassailable.
Johnson tested positive for stanozolol. Francis countered that (1) Johnson never took stanozolol since there were better drugs out there (2) that no one would take stanozolol during their peak racing phase as it wouldn't help and (3) the quantities found in Johnson's urine would have killed a small horse. Francis openly admitted that Johnson used drugs but made a very persuasive case that he never took stanozolol.
That's not proof just more BS, lies on lies
In any case he was caught 2 times just as Gatlin was. There is a site call steroid nation where the bodybuilders piss themselves about the excuses athletes like Gatlin come out with.
Having athletes like Gatlin back in the sport is an advert for would be dopers. how ever many time you get caught you can still come back