At 24 it wouldn't even be a question for me too.
But, let's say that you're the star hitter for the Houston Astros, a public figure. Would you be okay with pictures being taken with your awareness of you personally serving alcohol to an underage girl, and with those pictures becoming one of the most talked about stories on sports radio across the nation for at least one day, leading the owner and manager of the franchise to publically question your behavior, lessening the chances of getting your contract renewed, even after being benched for your play on the field? Leinart seems oblivious to all of that.
If it was baseball it wouldn't matter, because the contracts are guaranteed. And then you go play for the Yankees.
Granted, I am only vaguely aware of the circumstances of this thing, mainly because I don't care, but wasn't the party on his private property?
There is also the HIGH probability that the girl lied about her age. Girls do that.
There is also the possibility that he didn't care.
Also, the formula for the socially acceptable dating age ((.5*your age)+7) seems to work out for a 24 year old to
bang date a 19 year old.