Well, I think LSU is every bit as good as USC (though either one will lose to OU IMO), but aren't you overlooking one minor point?
LSU still has to beat Arkansas who is no slouch! They did beat Texas....
And USC still has to beat Oregon State, another team that could be a spoiler.....
Personally if I thought they had a chance to beat OU I'd like to see LSU in there......but since whoever faces the Sooners will probably get spanked, I would rather see USC play them.
Actually, now that I think about it, LSU has had a much tougher schedule IMO, and therefore deserves the chance at OU!