But by responding and admonishing that the person has violated the thread rules, it's also not wrong, even though the OP can delete when deemed not to comply with the rules.
I don't think it's necessary because if the OP deletes post that break the rules, then the response post after that must also be deleted because it's no longer relevant. But of course it depend on how the OP moderated this thread although so far I think moderators will delete anyone's post that quote your deleted post.