Yeah, a creative person can call their creation whatever they like, that does not mean it does not fit nicely in an existing genre.
He can and he did…That being said I would add a little more emphasis to his decision to call his creation that then some anonymous guy on the internet defines it. He wasn’t a rookie when he made SW and had been immersed in movie making and its history for some time. IOW he certainly knew what he wanted to call it.