This was recently brought up on the boards ( about what happens when you have your account deactivated.

Some people might like to retain their privacy, despite leaving the boards, and I think that should be respected. In those cases, I think if someone has set certain privacy settings in their profile (such as having the list of posts viewable set to "Only Me"), that should be maintained despite their leaving the community.

I think some people would prefer to have their account deleted entirely, but since that's not an option, this might be the next best thing.