I'm sure Elizabeth can speak for herself. Personally, I find myself agreeing with the points in her original post. I've observed a fair bit of this behaviour at various events Down Under. Sexism is often subtle, but it is there, and I find it distasteful, at the least.
I'm also prepared to give women the benefit of the doubt, in the sense that many women encounter so much sexist behaviour on a daily basis that, sometimes, they end up being on a short fuse and do or say something that men perceive as an over-reaction. If I were a woman, I'd probably be on a short (or much shorter) fuse, too. There is only so much crap I can take before I lose it…
As I said, if a woman says "I don't now how to play this game", I take that as an invitation to respond. If I then say "if you like, I can give you a basic run-down of the rules", I don't think that's being sexist; instead, I think that's being helpful, and it is no different from how I would respond to a man making the same statement. And, of course, the woman is free to respond "Thanks, but I think I'll give it a shot myself first and see what I can learn on my own." (I have been in exactly this situation many times, saying to someone "I have no idea how to play this thing." Quite often the response is "I can show you a few things" and, inevitably, I gladly take up the offer, whether the offer is from a man or a woman.)
I think the point here is that things become sexist when men assume that a woman needs to be helped and then proceed to help her whether she wants it or not. It's nice to ask first and be prepared to take "no" for an answer. Otherwise, the "offer" is simply an implicit assumption that the woman is incompetent.