This seems like a good thing to do as a courtesy in cases where it seems reasonable.
If it were an actual policy, you'd want to put some limits on it, i.e. "if the post is longer than X words and/or contains something that was clearly meant to be intelligent thought."
http://wiki.lesswrong.com/wiki/Deletion_policy
This is my attempt to codify the informal rules I've been working by.
I'll leave this post up for a bit, but strongly suspect that it will have to be deleted not too long thereafter. I haven't been particularly encouraged to try responding to comments, either. Nonetheless, if there's something I missed, let me know.