Although Berbatov has been threatened to remain on the bench, I feel it is Tottenham's right to make this decision. They may have reasons behind it that the general public is not aware of and it is ultimately their right to do as they see fit. Given that Berbatov is paid regardless.
While Berbatov is a talented athelete, his professional contract is held my Tottenham. It is up to the management of Tottenham to determine how they wish to continue with the contract they have for Berbatov. Though a change of team may be what Berbatov desires, it is the decision of his current team if they wish to sell his contract to any other team. If they do not wish to do so, it is fully within their rights to hold onto the contract for Berbatov and make any decisions related to how often, if at all, he plays.
It is fair for Tottenham to leave Berbatov on the bench because Berbatov is a contracted player that is paid for his service to be in the club, so Tottenham has the right to make a decision that he deems suitable for the player. It was also stated that Berbatov was declared "psychologically unfit" for Tottenham.
Berbatov's actions have reached the point where the coaching staff thinks he is a liability to keep on the field. He is not acting like a team player. If the staff at Tottenham want to keep him off the field, that is their decision. What will hurt this decision is if the football team loses with Berbatov on the bench. If they can secure a win without him, the fans will support the decision. If they lose, then high levels of scrutiny aimed at those who kept berbatov off the field can be expected in the form of beer bottles.
A sports player knows their own playing and their own body and their own morals, and there are many reasons for people to stay on the bench and just stay put. People Have to sometimes abdicate their responsibilities if they can't or won't do something that they are supposed to do.