The ground was never valued at £11M. IIRC it was valued at £5.5M.
Swann “wrote off” the £11M when he took the ground. He then sold it for £3M. An £8M loss.
He could have left the debt, and the ground with the Club. He could then have called in the £11M he was owed & bankrupted the Club. He would have claimed whatever value was raised from any sale of any assets. It could have been more than £8M, but it would probably have been less.
He was not a good Chairman at all. However, he could really gave shafted the Club big time if he had wanted to.