The reason he won't or can't sell shares until 2019 could be due to embarrassment clause inserted by the Bank when writing off debt. They will not want a shareholder to be able to publicly profit from the debt write off shortly after the restructure.
Perhaps a clawback on any share sale proceeds for the Bank if he sells shares before 2019 as opposed to potential financial implication for the football club. Staying on board will be important to protect any value in the shares until an exit in 2019. Possible EGM certainly concerning him, he won't want to lose that influence and control.