It’s easy to fake if you are part of YC. You think they would lose 1B+ potential revenue if the only thing they have to do is to change one database record that nobody except them is monitoring ?
it's pretty hard to unpublish something on the internet though. How many system do you think are consuming HN content? how many consume those? You can't un-ring a bell, so a simple social post is almost always discoverable in the future.