He means the matter we know as galaxies today.

Our current theory implies that our space we know and love (bound by our time, spacetime) expanded at that moment. We know we shouldn’t be seeing older galaxies that look younger than others we know to be young. That’s what’s implied by these findings at least - they could still be explained by other things we have yet to discover, because we haven’t finished processing this data.

The title is just for the clicks.