Exactly. Anyone can see where the posts are coming from that are a part of the RSS and create a account and get it added to the RSS feed. Since mods are on most of the time not all day everyday there are small windows where people can get a few posts up on the RSS without us catching it first.
The only way around it, would be to create a special forum where only selected people or Mods could move posts to that would be the RSS Feed. Which is kinda anti-productive.