Tony, that's pretty funny about your upside down comment. I never thought of it that way, about upside down glue-up automatically making the top flat
I made a small table a few years ago, and I glued together the legs and apron upside down too. It was easier, and I don't remember if I gave any thought to this helping to ensure the top would be flat. It just seemed to be the "right way" to do it.