Pointing out that someone has cheated in the past does contribute to a discussion of whether they are cheating now. It can be prejudicial, but it also goes toward establishing a pattern of behavior. It isn't as if PED use has been the only issue for which Cyborg has been accused of cheating. She has also been credibly accused of tampering with scales during fight weigh ins.
Is Cyborg using PEDs right now? I have no idea. I am making no such accusation. But unfortunately for her fans and for her reputation, at this point the idea that she is using is at least as plausible as the idea that she is not, and that is entirely Cyborg's fault.