Weigh-in weight with 24 hours to rehydrate doesn't mean much. Cyborg is 15-20 pounds heavier than Rousey at fit weight (based on Cyborg's post showing her at 175 pounds and Rousey walking around at a fit 155 in TUF. Unless Rousey has vastly better technique than Cyborg (and there's no indication of that), she's simply too small to beat Cyborg. There's a reason for weight divisions.
They could get around that by having them fight at 145 (or fairer, 155) with a weigh-in just before going into the cage. That fight would be a classic matchup, and either could win - because then they really would be the same size.
The difference between Cyborg and Rousey concerning PED's is that Cyborg failed a test, Rousey never did. That's not a double standard, its simply a fact. The debate then moves on to how long do benefits last - there is growing evidence that it can last decades (much of the tests done on mice admittedly - but then again, the tests that said benefits were limited in duration were also done on mice). The question of whether Cyborg is still benefiting doesn't have much to do with double standards, or even Cyborg vs Rousey, its a much bigger issue concerning how long suspensions should be. For instance, in the 2016 Olympics, America had a sprinter Gatlin who twice was popped, but was again allowed to run (and win silver); many feel that was unfair, and those complaining probably have never heard of either Cyborg or Rousey (MMA is a still a very niche sport, even compared to track and field).
And you're a smart guy, you know very well that its impossible to prove a negative in most things (binary questions in formal systems like math being the exception), so no it can't be proven that Rousey (or any other athlete in any sport in the world) has had an absolutely clean career. I'm kind of surprised to see that in your post, you typically stick to science.
I don't think it has much to do with Rousey getting victim status (she's extremely rich, I think most people would love to be that kind of victim), just that its decidedly odd to repeatedly call out someone who hasn't said anything for a year. But if its a question of taking offense at Rousey, I'd say Cain and GSP have prior claims to Cyborg (she said GSP was bad at MMA, and during a streak where he hadn't even lost a round in many defenses, interestingly enough Rousey has never said Cyborg is bad at MMA, just that she thought she was a cheater).
