1. Students are discouraged from reporting sexual assaults for fear of being investigated, and possibly kicked from BYU. Lack of reporting means that law enforcement, the university, Title IX office, etc. can do nothing to help.
2. Assailants have additional leverage over you, as compared to students at Universities without such a policy. Let's say you're a creep and you have two potential "targets"... one is a student at BYU, one is a student at UVU. BYU student is an easy target because you just have to remind the student that they better not report it, or they'll be kicked out of school. This is particularly enforcing if they know alcohol or some other HC issue was involved. Failure to report also increases the likelihood that there will be repeat offenses.