Hes not only serious, they intend to start in the next few years. Costs and space available restrict how much we can launch to the moon so that only things that cant be reliably made on the moon will be sent up and only the highest value things like 3He will be sent back.
If we waste money sending chicken legs and bringing back ethanol it will never work. If we only send medicine and high end computers up and send 3He and metal foams back then it makes a profit and is feasible tomorrow.
The market for o2 and ethanol is the LEO satellites.
NOT earth LOL!