Do you know him as in you have met him in person, and know the real-world name he has besides his screenname? I hardly know anyone on Hacker News on that basis.
Not fully on this subject, but found in a thread linked from another tread I just looked up about nickb, it's interesting to look at Paul Graham's comments from 2251 days ago about why he didn't want Hacker News to grow too big.
"It's a combination of motives: I want there to be a site that's like Reddit used to be; I want a real application to drive the design of Arc; and it's good advertising for YC.
"All three are best satisfied by a medium-size site with good quality links and comments, so I am definitely not hoping News.YC becomes the next Digg."
That said, I can not personally confirm Nick Bobic is nickb, but it fits pretty well and others in that old thread seem to be sure of it.