If they we're fighting MMA, I would totally agree. But pure grappling? I dunno. He looked pretty fecking humbled in the interview. I'm not saying he was going full power to beat Rousy... but he was certainly trying his damnedest to not get armbarred and he couldn't stop it. Thats impressive which ever way you cut it.
Yes. Full MMA with striking allowed, he'd probably KO her pretty quickly, but in pure grappling a big technique advantage beats a big strength advantage, that's what using leverage is about. And keep in mind she is a fricking bronze medalist Olympian. And once she has the setup, his arm muscles are not stronger than her back muscles anyways.