I think it’s hard to argue that the USSR wasn’t a military dictatorship under Stalin. The USSR was hyper-nationalist and relied heavily on extensive police and military forces that used excessive violence to keep dissenters in line.
The USSR wasn’t pursuing an ethno-state like Germany, but neither is the Galactic Empire. You might argue that despite the Galactic Empire being diverse in species, notably only white human men served as officers and leaders and dominated the military, but I’m not sure that’s an intentional world-building decision rather than that’s just how films in 1977 were made. I’m not yet aware if the USSR was known for being gender and race inclusive in its government or military structure either.
You made some good points, I concede I was being overly reductive. I think you made a great summary of it.
I edited my previous comment to reflect how you changed my mind.