Interesting. All of southern Bavaria sits on a mantle of clastic soils that overlie a thick clay layer which then overlies the bedrock. Since the clastic soils are largely derived from the Alps and its predominantly carbonate rock, groundwater in clastic soils tends to be hard and alkaline.
However, it appears that Paulaner is getting their groundwater from a deeper zone that may avoid the harder water above. Since they are a relatively small user of groundwater (compared to a city), they may be able to get away with drawing water from that deeper zone. Hopefully it will last.
Interestingly, Bavarian waters can generally be decarbonated fairly well into soft and less alkaline water that is more suited to brewing. Look at the 'boiled' Munich profile in Bru'n Water to understand the change that can be produced.