I am of the opinion that there is a middle ground that could be enacted. Since the law is not 100% clear in this area, the couple should be allowed to correct / remedy the situation by either establishing an oversight (transfer to a third party holding) or by returning the gold to the account.
Or perhaps the couple could create some paper “Gold Certificates” and transfer the certificates to a fiduciary, while keeping the actual gold in their safe. Seems like there’s a precedent for that.