I understand the feeling, but the site guidelines ask you not to reply to egregious comments (or comment on them at the top level, which is the same thing but worse). In other words: please don't feed the trolls. We've banned the account, but the damage that comment caused has now spilled over the entire thread.
If you flag the bad comment, that alerts moderators. In egregious cases, email hn@ycombinator.com so we can look at it sooner. But starting a new off-topic subthread about how shitty a shitty comment was merely makes the thread worse, so please don't.