I too have been lucky enough to hear him speak, and he very much does have this naivete of youth in the way he speaks. He has this very simple and straight forward way to view his contribution, along with a very simple motivation of "it makes me happy" that does feel naive.
I don't think he's nearly as naive as he comes off, but I think he wants to be seen as naive, because his personal philosophy is one that places naivete in high regard. He wants to follow happiness, and happiness can oftentimes be a little naive.