He's not perfect, but behind the scenes he's a genuine and upstanding person. I've met lots of wealthy smart people, and he's the only exception. He was the only person I trusted in this situation, and I'm genuinely nervous that he's no longer running OpenAI.
"Good" is too blurry of a description, and I don't know Sam, but one thing I've learned (the hard way) is that you don't truly know someone unless you've had conflicts of interest with them and found mutually satisfying resolutions to them. If all you've had is mutually beneficial interactions, then of course everyone's going to be nice - it's in everyone's interests. You need to see how they act on nontrivial conflicts (either handling present ones, or mitigating/averting future ones) to really know if someone is a genuinely good person or not.
While this could hypothetically happen within an hour of meeting someone, it's more likely to take years or even decades... or might never even happen.