There is no business case for Lunar He3 extraction.
He3 isn't as rare on Earth as most people claim. He3 is expensive on Earth because there is virtually no demand. If we ever get working fusion there will be demand and people will start separating the various isotopes. This will lead to a dramatic drop in terrestrial prices for He3. Shipping costs from the Moon have to drop by at least an order of magnitude, more probably three orders, for any profitable He3 extraction, assuming fusion power plants become available.
When a business case doesn't have any sizable revenue for at least three decades, it is not a business case.