Articles don't just gain points by direct upvotes. They also gain a point when someone else submits it.

I suspect that there is significant overlap between his regular readers and HN participants. People read his blog and submit it.

Furthermore, articles about writing and karma acquisition are often topics of interest to HN's readership, as are articles about HN.

There's no conspiracy needed to explain it. Not to mention that his karma score from comments alone would put the author on the leader board.