Yeah, 2019 LSU is allowing almost 10 fewer points per game than last year's Oklahoma team that made the playoff. So let's not get crazy here.
LSU is more like a XII team, that's completely true. And if their defense is that porous, it will cost them eventually. If they were to chalk out the rest of the season as the #1 team, they'll be facing Georgia, then whoever is #4 in the country, then the Ohio St-Clemson winner. One of those teams is surely going to bite the Tigers and expose that defense. And if they don't, then LSU will have earned their title.
National champions do tend to have very good defenses, so when the time comes to make predictions, that will be a huge mark against LSU. But let's get there first - a lot of football to be played.