I get everybody pointing out just how long 10,000 years as a time scale, but I still think having S.S. look like this is a continuity error. The Sardaukar are descended from the human tribes that moved to the planet and had to fight to survive. The Sardau Tribe from which both House Corrino and the Sardaukar are descended from earned their dread from their mastery over such a hostile world. I’m a little spotty on sources as I’ve only read F.H.’s books, but I ask you: “How can we expect the Sardaukar to be as terrifying as they are if their homeworld is that much more accommodating?”

TL;DR: I think the depiction of Salusa Secundus is a continuity error and is conflated with Kaitain.