Seems like he posted a lame joke. The appropriate response would be for other users to downvote him. I've seen his other comments and he'll regularly be downvoted, but I think you're overreacting a bit. Perhaps you should stick to making sure HN runs, and aside from that mind your own business?
Sadly, it's my business to deal with flamewars, personal attacks, trolling, and other abuses of HN. If flames are allowed to burn this place to a crisp, HN won't be HN anymore. And eventually there wouldn't be anything worth running or anyone to run it for.
