It was always about the very technological imperial US, who at the time happened to be fighting Vietnam. Lucas talks about how the Empire is “10 years after Nixon makes a coup in America and becomes president forever” and stuff. In earlier drafts there’s even annotations like “Make Rebels more like the Viet Cong”. Leia’s hairstyle is reminiscent of Mexican revolutionaries, when it came time to pick an astronaut outfit for the Rebels Lucas decided to go for the Soviet orange versus the American white. Honestly baffling anyone would really dispute any of this, Lucas has been saying/writing/etc about all of this since forever. Not at all a contradiction or a rewrite of history.