Another option would be to have
OldScammerTag leave negative trust whenever someone meets the above criteria of waking up their account and having not changed their password since the May 2015 hack. This negative rating could be removed after a signed message is provided, or after xxx number of days from when a user disputes the negative rating publicly -- in the later case, the rating could be changed to a neutral.
That honestly seems like a lot of extra work on the admin's side. I highly doubt anything like that will ever be implemented.
I didn't know this happened now so thanks for the thread. Hopefully it should help some people who are too trusting to realise that they should get some sort of proof that they're dealing with the original owner. Maybe just maybe this will prevent some scams from those ancient hacked accounts.