If you think your website is "worth enough", you can make it a paysite and raise the barrier very much: see Metafilter (which has a 1 post/day hard limit, except for the owner)
Once your site is big enough, it won't really be a problem.
In fact, it's unlikely to ever be a problem: if your site is small, nobody on a bigger site is going to care about a someone bitching about it, so the story will get buried. If it's large, any site worth its salt will delete a griefing post to avoid the inter-site grief (see: reddit deleting the posts that lead here, mefi deleting pretty much anything leading to LGF)