Because unlike Minnesota where the ground pretty much stays frozen year round, down here it thaws quite frequently, causing a sloppy mess. Heavy foot traffic on dead grass with mud underneath just tears up the grass which has no chance of regrowing. You end up getting pretty bad erosion.
Other courses get pulled because their fairways get used for cross country skiing in the winter.
There is another 18 basically across the street from the original 18 at Parkside, but from what I hear it's nothing exciting. The course has a lot of disc-eating prairie grass off the fairways so depending on whether they cleared it (if they clear it even) for the winter, it may or may not be worth playing.