A poster's entire history being deleted 'at poster's request'.
I realise it has happened when there have been serious issues regarding someone's personal privacy, being outed or somehow being made to feel vulnerable/threatened in RL as a result of what they posted on MN, but why else?
I thought your policy was not to delete posts (providing they fell were within the TALK guidelines) unless they seriously compromised someone's privacy or safety, or there was potentially a legal issue.