Even with the end result, I would still disagree with that statement.
The Horns are the national champions, but that does not mean the Trojans were inferior to them. Sports history is replete with instances of the better team (on paper at least) losing in one "winner take all" game, a la Houston in 1983, Georgetown in 1985 and UNLV in 1991...those examples being college basketball of course. I don't know my college football championship history well enough to cite football examples, but I'm sure there are some.
In fact, having watched the game, if those two teams played 10 times I'd still feel comfortable wagering that USC would win at least 6 of them.
Even so, Leinart probably should have just kept his mouth shut and avoided looking classless.