This isn't staging of materials
The current plan is to build a small core. What we want to do is to test our radiation shielding. We want a, at least partially, manned station so we can test multiple concepts using the same platform. We can do that anywhere outside of the Van Allen belts. It makes sense to put the test station in Lunar orbit because if someone decides to bother landing on the Moon for commercial purposes they now have a potential customer.
If we want to consider exporting anything from the Moon we have to build a colony. We might be able to build a Lunar factory that can fix itself but it will be insanely expensive at this point. It will be far cheaper to just hit something with a spanner, when needed, than to try to make all of the equipment fail-proof. We can build spanner wielding robots that reduce the need for meatsack spanner wielders, just not economically eliminate them completely.