As I said before, in an empty universe it's all moot (more extreme than the "if a tree falls in the forest and there's no one there to hear it" question). But following the Big Bang the universe was not empty; it did contain energy and matter. So your objection is beside the point, unless I'm missing something??
We agree. My original assertion that "space without matter/energy is an oxymoron" was in the context of the "Big Bang" event. IOW an expanding universe wasn't merely expanding "space". Some believe matter/energy was "created" ex nihilo and simultaneously expanded, i.e. became less dense, within an expanding space time continuum.
The misunderstanding was in the use of the word "space". Our current theory/understanding of a "space" is a volume that contains "nothing". Whatever that may mean. The universe is thought to contain mostly space, i.e. nothing. But in the 19th century we used to think it consisted of an "ether".
I heard someone recently speculate that "space" is really "quantum foam". And of course there's also the theory of "dark matter".
Strange stuff.