He named it, so is ever so slightly wrong - but all of us who have been around for a while and have participated semi-regularly in discussions without getting banned are in. Relative to the global online population this is still a very small group.
I don't think that's quite right. In Lewis's thesis, you only really encounter the in/out question by interacting with people who are in. By your definition, interacting on HN puts you in already. And "and have participated semi-regularly in discussions without getting banned" is a much lower bar than anything Lewis is talking about. You'd have a much better point w.r.t. lobste.rs or other invite-only forums, but the whole concept is dubious without private discussions.
Granted, but I'm not saying that just posting and commenting on HN, or passing the various gates, constitutes being 'in'. Even having high karma isn't 'in'. I don't know if I can articulate what counts as being 'in', but certainly participation in a YC round is part of it.
The latter quarter of the article goes into depth about how one can accidentally find oneself in an inner ring, but it is through a wholesome pursuit and no ulterior motive. The other reply to this comment gets it write: people here like interacting with the things on HN.
In other words, to comment on HN does not mean you are striving to be in the inner circle.