I am not a fan of Zuckerberg, but I don't think you have any right to claim such a thing. People can change.
It's good to hear you were so responsible at age 16, but not everyone matures so quickly. My own personality has basically done a complete 180 since my high school and uni days, from the biggest prick you ever met to someone who genuinely tries to show compassion and consider others' points of view. Is it all a façade to conceal the inner asshole? I'm sure you could make that case, but in the end it's outcomes that matter. They say the road to hell is paved with good intentions, but the flip-side of that is that sometimes people who might still be assholes internally can do a lot of good.
Track record is important, yes. But giving sincere people second chances is also important, and that goes for Zuck, too.