That said, even if you did redefine the concept in the way that you mentioned, the term "astronomical waste" still implies an emphasis on taking over the universe - which is compatible with negative utilitarianism, but not necessarily every ethical theory. I would suspect that most people's "folk morality" would say something like "it's important to fix our current problems, but expanding into space is morally relevant only as far as it affects the primary issues" (with different people differing on what counts as a "primary issue").

This is getting a bit far from the original topic, but my personal approach to handling moral uncertainty is inspired by Bostrom and Ord, and works by giving each moral faction a share of my resources and letting them trade to make Pareto improvements. So the "unbounded utility" faction in me was responsible for writing the OP (using its share of my time), and the intended audience is the "unbounded utility" factions in others. That's why it seems to be assuming unbounded utility and has an emphasis on space expansion, even though I'm far from certain that it represents "correct morality" or my "actual values".