Okay, here's the deal. It's okay for people to vent on THEIR blogs about things. The main golden rule is that you may not put the person's real name or full handle into the title of an article (since JoeUser is so popular, what you write here ends up on Google pretty quickly).
That said, you post it to the forums and then it becomes our business. When you make an article, by default it has a checkbox that says "post to forums too". If you're writing something that is essentially a rant about some other user or anything else that really doesn't belong in a public forum, you need to uncheck that.
Right now, there's a glitch on JU where I cannot hide a forum post without hiding it from your blog as well. So here's the deal: It's up to you to uncheck that "post to forums" option if you're about to write a rant about someone. Otherwise, it's likely going to just go away entirely.