> piping oxygen from the south polar mines to bases where humans will live

Regolith is roughly 50% oxygen by mass, it will be far more practical to just crack it out of minerals than pipe it across the moon from polar craters.

Water can be cracked into hydrolox propellant, but Starship doesn't use hydrolox, avoiding it due to the difficulty of handling and storage and its low density. At any rate, the great majority of the propellant mass is actually oxygen, which...again...can be obtained anywhere on the surface. Starship could take on lunar oxygen after landing, getting 78% of its return propellant from lunar sources, without any dependence on polar ice.

Which is good, because it's not certain there's enough easily-accessible ice at the poles to burn as rocket propellant. It may be better to conserve it for uses on the moon itself.