Userids are embeded in so many places you risk doing a lot of damage, besides which if he was deleted properly, all his posts would have been set to guest anyway (userid 0) so there is no way to get them back.
The thing is it apparently deleted itself. No person touched his account... it just disappeared for some reason. I hadn't messed with anything that day... it was just gone. His postbits only have his username, nothing else. His name disappeared on the Memebers List and his member profile disappeared... everything. But it still recognizes the username on posts only. It's odd. :surprised: