This is not an exhaustive list, but the following is in UNC's response to the most recent NCAA report.
The NCAA has oversight over athletics but not academics. Therefore it lacks jurisdiction over many of the alleged violations
The sub-standard classes were taken by both athletes and non-athletes. While 30% of the enrollments were athletes, obviously a disproportionate amount, North Carolina claims the percentage was irrelevant because they were available to all UNC students.
There is nothing inherently wrong with a student enrolling in a reputedly 'easy' course whether the purpose of taking the course is to balance the student's schedule, remain academically eligible to be a full-time student, meet academic scholarship requirements or to simply boost the GPA.
Personally I don't think these arguments will fly. Syracuse was penalized harshly for lesser academic violations. However, they probably are making the same case to recruits that they have made to the NCAA except that they're telling the recruits that the arguments will be effective.