The published version, with opening html paragraphs (except the first one, for some reason) and with html entities translated back into single characters, comes out to 1979 characters.
Your second link, formatted the same way, comes out to _exactly_ 2000 characters. The limit could potentially be strictly _less than_ 2000 characters. You may have been exactly one character off.
[1] https://hacker-news.firebaseio.com/v0/item/17388936.json?pri...