Are you talking about Tom's site? If so, its a private blog, so I assume that he can control which comments appear and which do not appear, its not at all about upvoting and downvoting, of course there aren't any rewards.
Also, in my experience on blogs like this, authors have to 'approve' comments so they appear, before which they won't, and it's a manual process that could just have not been done yet.
A private blog. I have no question. But here in HIVE, that is a problem.