Granted DUI is a bigger issue than the past transgressions, But Neil will (probably) get game suspensions and probation with the HC. Worst case (and most likely) he'll have to sit the entire season.
They guys that left BYU in the past did so on their own... or flunked out. A current Ute Linebacker had multiple HC infractions yet still had the option to stay in school and sit a year. And that was already AFTER getting suspended for a Bowl game.