They brought the breach to the attention of the FL who judged the infringement and punished the club at the time it happened. From that angle, Sunderland have admitted a technical error that the authority have punished them for. The more recent stuff is simply a straw man being built by a resentful media. The fact it happened quietly in the background seems to imply it's the normal practice for minor technicalities like this. The player had been with them several years, had a brief spell abroad before returning. It's not an obvious **** up to not realise another form needs filling in. If it had, it would have all gone through anyway, so nothing's really been gained.