I'm pretty sure this falls under rule #1:
Is there any better option to force moderators to nuke and delete all your posts?
That might be a good option if you don't want to leave any X posts in archival board.
Personally i'd say there's no need to do anything since these days this message is shown if we attempt to report old posts,
Old post: We generally do not moderate posts this old for on-topicness, substantiveness, multi-posting, and other "cleanliness" issues.
Almost no one read thread/reply on archival board, unless they specifically need to look for certain posts.
Great tool, but why delete in the first place? Even if someone deletes all of their posts, the data remains in the archive and ninjastic. Anyone can type your username and look up your previous posts.
Not everyone delete their post due to privacy reasons. I've seen few member claim they delete their old posts because their old post could be considered as spam or has outdated information.
OP, can you make a script that can delete personal messages? The script should have an option to select a specific user and date range. From which to where you want to delete. It might be very useful. Especially for those who get thousands of PMs every day.
But how many people receive such amount PM? Even popular user such as admin, moderator or campaign/bounty manager probably receive such amount of PM per month (rather than per day).