The premium ticket has been answered as of a few hours ago; it was escalated internally due to a migration error which needed senior staff to intervene. Long story short, free-hosting migration option was selected, but there was no free hosting account to migrate - the account needed to be restored from Premium backups from when the account previously existed.
I do apologize for the delay in resolving this, but in the future if the account needs to be restored from a pre-termination backup we would recommend leaving the "free migration" option unselected, as that will cause problems with account provisioning if there is no free hosting account to migrate.