It appears you have been hellbanned (as of this comment: https://news.ycombinator.com/item?id=4026814 ). You might be able to appeal it by emailing pg, or just create a new account.
Recently I've been seeing a number of good HN posts auto-killed because of a post or series of posts from the author a while back got them shadowbanned. There must be a better way of dealing with people who aren't obvious BUY WATCHES ONLINE spammers.