I think they both were some points in their careers, its possible thats why rivas looked like crap his last fight and why whyte got flabby.
Whyte is proven steroid cheat so he should be banned for life. You can kill someone in ring especially when in PEDs.
I often wonder why they don't take a zero-tolerance approach. The length of bans in boxing often seem more like a slap on the wrist as if to say try to be more discreet in the future. I also question the use of back-dated bans if the athletes were happily competing. Whyte isn't a "proven steroid cheat" though. But going back to the above, Whyte tested positive for MHA in 2012 and was banned for 2 years (I believe with the first year back dated). Stiverne tested positive for MHA in 2016 and was given a fine by the WBC and allowed to fight Wilder.
Looking at them, you'd think Rivas was. He has those massive traps which are often a tell tell sign of steroid use.
I have a very simple solution. If you are caught on PEDS, you don't serve any suspension at all, you are just NEVER AGAIN eligible to fight for a title. Simple. If people want to see the Big Baby Millers of the world fight, let them fight, just not in eliminators, or championship fights. They can take all the PEDS they want and fight each other.
To get a 6 month ban when you fight once every 9 months? Devastating. Step one and the bare minimum is that positive tests should be counted as a DQ loss and the winner should get paid. I hate seeing guys have to go fight a proven juicer because the rent is due.