OTOH, and this is pure speculation from an ordinary user and I specifically would *NOT* expect any admin or moderator to confirm or deny:
*IF* Dave agreed a deal with the ex-user in question that in exchange for eradicating his content he'd avoid any future interaction with this forum or the rest of Dave's online presence, it may have been well worth it (excluding the unforseen database corruption, which no doubt would eventually have take the forum down anyway). Its a simple choice to spend a few hours *now* and accept a limited amount of loss of content, to avoid a pissed-off and technically competent
nutter person gunning for you, vs dealing with the sh!t they are likely to attempt to fling for the foreseeable future, if you don't give them a perceived 'victory' as they depart.
I do however believe the forum rules section:
Removal of Data:
You are free to delete or edit your own posts at any time. However, once someone has quoted your text (or it's archived by another website), you can't remove that, and only under exceptional circumstance will moderators remove it for you. This is at the discretion of the forum owner.
Basically, whilst you are allowed to withdraw your own posts, please be aware that it may have already been copied and duplicated elsewhere.
That is always the risk of posting on the Internet, and this forum is no different.
By posting on this public forum you are effectively giving up ownership of the text you wrote - it becomes public domain - people are free to quote it for perpetuity on this forum and other websites, bots are free to archive it and make it available in searches, and the forum owner is free to archive it and restore it if desired. You have no right to demand that what you wrote be removed from all parts of this forum and other people's posts. If you don't like this, don't post to a public forum like this.
could do with a tweak. changing "You are free to delete or edit your own posts at any time." to "Registered users in good standing are free to delete or edit their own posts at any time." which would bring it into line with the actual situation: that banned or suspended users cant delete/edit their own posts because they cannot log in to do so.
Edit: I retract any inferences about the ex-user's mental state.