I just want to restate what jen_h said: Everyone should turn on showdead and read that comment. In addition to the comment being comprehensive, they also claim to have worked for the NSA. If that's true, then they have a unique and important perspective on this issue.
When someone lets us know about them, we unkill good comments that should obviously not be dead. Since there are too many posts for anyone to see them all, we rely on all of you to help us. The reliable way to do that is by emailing a link to hn@ycombinator.com. General complaints are less likely to reach us, for the same reason that the original problem probably didn't.
We have a plan that I'm optimistic will greatly improve this situation. It involves turning most of this moderation, including what's [dead] vs. not, over to the community. But we don't know yet when we'll be able to implement it.
You can email the mods about stuff like bans you consider unfair at hn@ycombinator.com, in my experience they are very responsive.