That's IF there is such a policy, but why would there be one? Why would it be for the good of the site if this weren't disclosed? Do you think that this warrants discretion?
I don't, but the powers that be do. If you read the occasional submission with that site that documents HN's behaviors that aren't listed on an HN page, you'll see it lists certain things like needing 500 karma to downvote but you may note that some behaviors repeatedly reported in the comments are never added to the site. Is that on purpose? I don't know.
HN is a good site with good discussion. You just have to accept that sometimes you're going to get muted with a "you're posting too fast" message even when you've only made two comments in the last twelve hours, neither of which are flagged, and both of which have positive scores.