I don't know if there is an official stance, but in all likelihood I suspect the full game will either have a delay for posting (and thus downloading) creatures, so they can be reviewed, or there will be a way to report inappropriate content (at the very least to set preferences as to what can and can't be downloaded on ones computer automatically).
Side note, for those who do have the Spore Creature Creator, you can log onto
www.spore.com and search for Lavos. I am glad to see that there are currently 12 or so different versions of Lavos (and 11 of them look really good ...) I didn't realize how amazing the creature creator could make it until I saw other people's.