Maybe the particular edit you pointed out was harmless, but it could be a warning of harmful edits that have already, or will in the future, happen. If the logic that the bot is following is to take a page range from a database and overwrite a page (or range) provided to an editor, then sooner or later it will make harmful edits. So the logic should be simple; if the page or pages parameter is present and non-empty the bot should not edit it.