I realize your inentions here, but why? There is no benefit really to deleting something as opposed to hiding it, and if someone posts something that they shouldn't, then deletes it, how would we know that they ever posted it? Duplicate accounts have even been found because the person commented from the wrong account, and then hid it. If that person had deleted their post then we wouldn't have caught them. It's a good idea, but it isn't really practical.