A counselor from another JC answered this 40/60/80 question for me. They want the redshirt athletes to under enroll for at least one semester to keep them from reaching the point where they invoke the 60% part of the rule while still at the JC. It is very difficult to meet the 60% while still at a JC so they don't want the athletes to have 3 full time years of enrollment at the JC if possible.