For Isak to have publicly made this statement it is completely a mind made up to leave, he wants no club options only Liverpool.
Some critics are of the opinion that it is the right of the club to agree to sell him or not and he doesn't have a right to force the club on selling him since his contract with the club has not expired. They describe his actions towards Newcastle united improper.
But they miss the part in Isak message where he mentions that promises were made in closed door and it can be deducted that Newcastle united has broken theirs to have let Isak furious of leaving by all means.
They can call it whatever they feel like it still doesn't change the fact that the player has made it known to the club and everybody who cares to know that he doesn't intend to stay but to leave and join his preferred club which is Liverpool. Newcastle are only holding him back because they feel he can one day change his mind and again they haven't gotten a replacement yet which is now a problem for the management, so it is either they get someone before the deadline or they lose both ways because Isak doesn't have it in mind to play for the club so they need to act fast.
Nobody knows the kind of promises they made but all we know is that they have broken the promise and that was why he came all out to the public to let everyone know why he wants to leave, many people need to get it clear before judging the player, is like hearing from both sides and again, the board won't come out like Isak did to let everyone know why he choose to leave.
When players have set on to leave a club what the club can do is to work ways to convince him to stay, if force is used to keep the player against his will it will be chaos for the team.
He can disorganise the team play to frustrate the club and benching him won't stop him from earning his wages. Newcastle should release him for the money Liverpool are offering puts Newcastle united in large profit to what on a normal Alexander Isak is worth in the market.
If Newcastle united decides to punish him for his actions by not selling him until his contract expires they will be in the losing wing, because Isak will still sign for Liverpool as free agent to the overall perk of Liverpool.
Honestly you won't blame the player since he had already said it that he wants to leave, maybe he might have seen that the club doesn't have what he wants after how many years of playing for the club. Isak is a good striker and no club would want to lose such player but on this very case the player need a change and whatever the conditions they agreed on I feel is time to let go even if he still has 3 years with the club, keeping him will never make him play with his mind, the best is to free him instead of holding him and expect him to start smiling with the board and continue playing, no it won't happen.
True, punishment won't solve anything, not playing for the club for 3 year and leaving as a free agent it will be Newcastle that will lose but still that move will reduce Isak's value and I don't see why they'd invite him when it gets to the international break, for me I'd wish to see both parties coming to an agreement because this won't help any of them, either the player orbthe board.