I honestly don’t consider Wikipedia a good enough resource in this instance on the exact definition of space opera as automatically under the umbrella term of science fiction, Wikipedia is good but I doubt the author of the article was diving deep into the minutia of the semantics they were implying, unless explicitly stated.

Understand where you are coming from by saying it is not only science fiction if it applies hard science, and it would be disingenuous for anyone to say Star Wars doesn’t contain elements of sci-fi, but I think there’s some similar biases in making space inherently science fiction. This doesn’t discount the droids, blasters, tractor beams and photon torpedoes, but I think most arguing fantasy believe those aren’t quite as muddled by the usual fake tech jargon. George did know what he was doing, he never even brings up how a lightsaber is made, too much Errol Flynn heroics to dwell on kyber crystals. Reminds me of the pitch that never came to be I believe at Warner Brothers to produce an adaptation of The Odyssey with Brad Pitt (roughly close to the time Troy was released) except set in space, in a way without changing much anything else, really trading one unexplored ocean for another, does this mean sci-fi really only needs a coat of paint for consideration? If so…then, well sure I guess that’s fair enough. But I think you had it right when you said Lucas needed to distinguish his movie as more on the side of Flash Gordon than movies like 2001, which is less relevant now because Star Wars mostly succeeded those. The heart of Star Wars is much closer to Wizard of Oz than most sci-fi and that’s how those like myself recognize it first.

Honestly though my truthful opinion is that other genres have just as much crossover and ambiguity but there’s more debate on what qualifies as sci-fi or fantasy because we’re all nerds.