Why does that feel naive to you, though? To me, that seems like an issue with your definition of naivety.
Like, he doesn't see the malice in other people, but its not because he's innocent/naive of such intents, nor does he lack the skills to look for it (guileless), but because (as you say) he doesn't care if people take advantage of him, up to a limit.
Properly calibrated, that's really admirable.
But being vulnerable is sort of an important part of being authentic.
And authentic people might have more opportunities to connect with others, especially with the limited time we have on this planet.
Where does this need come from, to be skeptical or suspicious? Of someone so clearly above board?
Wozniak doesn't need to prove himself to anyone. Maybe he feels comfortable enough in his shoes to be very open about himself, and so motivate people to be true to themselves. At least that's my interpretation.
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.