Artifact of organization. My degree came through the college of engineering, which required physics and chemistry for all grads. And some technical breadth electives, too.
Michigan is a... unique beast. Anything worth doing is worth doing a minimum of twice, preferably with no knowledge of other attempts. This is why there are two entirely separate radio stations.
Mine required 2 semesters of physics + labs and then a semester of any other science class.
But yours required physics and chemistry? I can't imagine why chemistry is required for CS.