Click your username at the upper right:
Turn on "showdead": showdead: yes. (defaults to "no")
There are a number of dead posts in this thread. I'd post some here (some of which don't appear to violate any HN guidelines, I'll note), but probably those same moderators would kill this one, too.
https://news.ycombinator.com/replies?id=<CommentUserID>&by=<ReplyUserID>
E.g., dang's replies to bigbacaloa:<https://news.ycombinator.com/replies?id=bigbacaloa&by=dang>
That (presently) turns up two admonishments dating back 11 months and two years: <>>37423572 > and <>>33132910 >.
The first of those (11 months ago) is where the account was banned.
If you have specific questions on accounts, users, sites, comments, posts, etc., which you feel are improperly flagged, killed, or banned, you can always email the mods at hn@ycombinator.com. I do this frequently, usually with suggestions (e.g., title or URL changes), sometimes with questions (earlier today a site which showed up dead, turns out it's a hard paywall, which I eventually tracked down dang's comment on, though not in an easily-searchable way).