That's my point though, now that he won this trophy even a mutual agreement makes no sense for him.
Why would he lose money (compared to the scenario where he gets full compensation by waiting to get sacked) AND move on to a smaller job AFTER reaching the biggest height of his managerial career? In his mind he would be succeeding downwards.
This cup win has changed the whole dynamic of this situation. He has the leverage now. He either keeps the biggest job of his life, or gets sacked with his reputation intact+ a hefty payout in his pocket. Win-Win for him.