The Ruddock your describing never actually existed at the elite level. By the time he was a contender he had already discarded his jab or any real semblance of boxing skills. The wins over Smith and Dokes both shop worn ended up hurting him as a fighter. Moorer was measured and at times too economical with his attack. With that said he is not going to let a guy get away with leaving himself wide open throwing uppercuts from way outside. That short quick right hook by MM would deposit Ruddock to the canvas. It would be a natural counterpunch. That is when Michael wasn't pumping the jab in Razor's face.
It depends on which Michael Moorer we are talking about. Moorer was chinny so Ruddock could take him out. When Cooper did knock Moorer down he got up and fought back and stopped Bert Cooper. When Evander Holyfield knocked down Moorer he kept getting up. George Foreman knocked Moorer down and out and he didn't get up at the count. Against David Tua I heard Moorer had developed a alcohol problem. Ruddock was able to handle Mike Tyson's power so at his peak Ruddock would take a punch reasonably well. Could Moorer hurt him? If Moorer couldn't get Ruddock's respect then Razor would win. If Moorer could hurt Ruddock then Moorer would win.
I think its worth noting that Moorer lacks any stoppage wins over highly ranked opponents. He stopped some journeymen/gatekeepers but to my knowledge never scored a knockout or even a knockdown against someone I would consider world class.
He beat one though. He may not knock Ruddock out but he could catch him off balance and score a knockdown or two. All of the guys Razor knocked out had seen better days. At the very elite level its almost impossible to win without two hands and some type of way to set up your attack. Telegraphing the same punch is a bad recipe at the championship level.