Doesn't really prevent accounts being sold, and then claimed back though. I'm not sure what the forums stance on selling accounts, and who the rightful owner is, but I assume that they would look for information that might indicate that the account was sold, and see if the credential changes link up to that too.
An automated method to claim back your account could severely reduce account sales. Who's going to pay hundreds of dollars for an account, knowing the previous owner can claim it back at any moment?
Losing your bought account will just become an occupational hazard.
Or just severely increase account scams when sellers just take their accounts back after they've sold them. Most newbies won't be aware that they can be reclaimed in such a way and falling victim to this will become rife (unless theymos has though of a way to stop this). I still think we should allow users to purchase the bigger signatures via donating for Silver and Gold Membership etc. This would essentially kill the account sales market and account scams with it so it's win win for everyone and the forum gets the money instead of some account farmer or scammer. Users don't get scammed, the forum gets the money and users can have the bigger signature which is what they wanted in the fist place.
I also wonder what will happen to those users who can't sign a message posted here because the hacker deleted it but the address can still be found archived online or on one of the bitcointalk mirrors etc. There's also the issue of those who don't have a bitcoin address but can sign one from an alt coin wallet. I'm going to assume theymos' auto-recovery system will be bitcoin only?