I disagree that one strategy is 'sfnal', or that it's meaningful to talk about 'sfnal worldbuilding'. I think both (all) strategies have been used in all kinds of fiction.

Undoubtedly they have. That doesn't change the fact that, by and large, SF focuses on explaining to the audience how it's world works and non-SF focuses on it's characters. That doesn't mean that SF can't do character or that non-SF never has to explain it's world, but that difference in approach and emphasis seems to me a reasonably good way of distinguishing the two.