I do think that’s unrealistic to be honest
Firstly if the offer / ambition wasn’t right he’d have to give the owners time to respond to what he thought would be suitable before simply walking.
Secondly he is contracted until the end of the month. I assume he’s been clear with them that if the offer doesn’t match what he was after then he’d go. So he’d simply wait to see.
Thirdly the owners have had plenty of time to know that if their offer wasn’t going to change that they needed to get someone else, and no doubt they’ll have been looking for that. So why wouldn’t he simply do the same, particularly as he, unlike them, wouldn’t be sure they wouldn’t change
Fourthly (this list is longer than I expected it to be when I started!) It’s not like he’s walked out of a contract and moved to another club. The owners didn’t give him a contract earlier in the season past the end of this month. All he’s done is work the contract they would give him. No reason whatsoever for him to do anything different, particularly if there was a clause that said he’d have a penalty if he walked before the end of the contract.
All this is down to them not negotiating an extended contract earlier. If they had then either he would have signed it, or he wouldn’t and they’d have known months ago they needed to replace him. They think they’re clever doing everything late, but they’re not.
He owes us nothing. He was contracted to do a job until the end of the month and in my mind he’s done a good job while employed.
I wish him good luck in his next job