This might theoretically be copyright infringement. Since Aaron didn't specify any license (like CC) for his blog, reproducing his content without his estate's permission is technically illegal.
Since his mother appears to have registered an HN account today, we could ask her directly.
Aaron knew about copyright's implications - hell right around the time of RSS, he helped launch Creative Commons. And he didn't put a license on his site. So maybe by not stating a license he was making a statement about copyright. But now we'll never be able to know for sure.
Unfortunately, the same might be said of Martin Luther King and his "I Have a Dream" speech, which still can't be reprinted or rebroadcast in full until 2038, thanks to the greed of his estate.
It's a shame that legal technicalities can end up being so important, but the fact is that it's true.