If LSU loses and OSU wins, LSU could potentially miss the title game. The voters wouldn't vote OSU any lower than 3rd and the computers would probably have OSU a unanimous #1. There is too much risk for LSU to throw the game.
Not unless LSU gets completely smoked. See 2003 OU. As long as they arrange it so that Georgia narrowly wins, its 3 from the SEC!
See 2003 USC, who was #1 in the human polls. The computers favor the Big 12, and LSU losing would all but guarantee an OSU national title appearance if they beat OU. The only question is whether the Cowboys would play LSU or Alabama.
Even if LSU wins, if OSU wins and 25% of the voters vote OSU #2, OSU will play in the title game.