I guess it depends somewhat on how sexual assault is defined. What does that mean exactly...particularly on a college campus? Forcible intercourse, or fellatio? Copping a feel? I really don't know.
I'm guessing if it is the former, the girl would most likely bypass the school and go straight to the police.
I'm guessing the board/committee sorts out more interpersonal drama than facts. Binge drinking makes it even more complicated. As the girl in the interview said, you hear two stories that are nearly identical, except for a key point or two. I'm sure the guys who confess (and who are not expelled), are not confessing to forcible rape.