He's obviously well educated and knows a lot about his field. I don't think he was trying to be untruthful in any way. I think he might have some of the hubris that comes from being young and newly successful...He's probably used to being the smartest (or at least most educated) person among a group of people, be it a class of his students, the cops he works with, or at the neighborhood barbecue (do they barbecue in Nebraska???) Although they are masters of different domains, JA is clearly an intellectual equal, who gave him a run for his money.
In the end, I'm not sure it matters much. If there is a juror who believes she is guilty, I don't think this changed his/her mind. If there is a juror looking for a reason to find her innocent, I think they may have found something in his testimony to hand that assertion on. For the fence-sitting juror, I think the questions of if Caylee was in fact murdered, and if so, who did it are going to be more important than questions about anything that happened after the fact. JMHO.