Defensive backs do this (and are coached to do this) in practically every college football game because they know that it's better to get a 15-yard penalty than to give up a long TD.

UU defensive back saw what was happening and decided it was better to (potentially) get yelled at by Whittingham for the penalty than if he gives up a 90-yard TD pass. And luckily for him, KW is a huge tool and decided to yell at the refs instead of the player who committed the penalty.