I got an e-mail about a week ago (yes I'm that far behind) from the owner of this account: https://e621.net/user/show/76555
They claim that they're not the person that the ban message says they are. It seems that only one IP has ever been used for that account, and it doesn't seem tied to any of the accounts mentioned in the ban reason.
If anyone has any further information on this, please let me know. Otherwise I'm going to be forced to unban for having no proof on our side.
Updated by ippiki ookami