Maybe he deleted it.

I know we are free to remove own items but when it comes to surveys it is not a good practice. This can lead to the habit of removing surveys, results of which we don't like.

One aspect I like on this web site is that the operating principle is that the creator of post is in charge. This publishing control comes with responsibility. That is, if a user keeps posting a content (survey and/or other types of post) and later deleting it, well, other users will eventually notice and won't take him/her seriously anymore.