Sometimes posts get put on the "try again" queue by the moderator, where they are floated to the bottom of the home page to see if they will attract attention the second go-around. I don't know if that's the case here.
Ah indeed, the Ask HN itself is from the 14th and various comments are from then as well. Seems like it got put through that process which causes HN to "fake" the short timestamps to make everything look like fresh discussion.
