The only thing unusual here is the call went against USC. The Pac-12 has a history of helping USC, especially when the Rose Bowl bid was on the line. For years Pac-12 official felt USC was the only team that could beat the Ohio States, and Michigans coming out west from the Mid west. This goes back a long ways, of course.
There the infamous Paul MacDonald incomplete pass which was actually a fumble ND recovered. The ball went back to SC who then kicked a winning field goal. The play where their running back was stopped on the one yard line but the official ruled he had jumped over the pile, scored and was pushed back. ND lost by less than a touchdown. It was John Robinson's last game and the rallying cry had been, "Win one for the fat man." Yes, the official did. UCLA has been screwed numerous times by Pac-12 officials re USC.
Nothing he Pac-12 does surprises me.