I'd agree that it functions primarily as a theoreticall statement. I think "everything is made up of atoms" functions the same way; atoms are defined as those things out of which everything else is made uip. IT's not as if atoms and everything are floating in some real world somewhere, and we already have the concepts 'atom' and 'everything' in our head, and we go to the real world to see how they hook up. It's a statement of scientific theory, not scientific empiricism.

But it's still not meaningless. (Again, the synthetic a priori, but instead of one permanently fixed into our conceptual catefories, one which is contingent and arbitrary.)