The conference didn't win the game, USC did. Most of the conference probably felt like they lost the game (not the game vs. Penn State, but the selection process) weeks before January 1.
This has absolutely nothing to do with the game being great. It was. It has absolutely nothing to do with the Pac 12 rep winning the match up. If a 4th place Pac 12 team not named USC had been selected, this board would have been on fire in the other direction.
If you can't figure all of that out, I don't know what to tell you.