Even if he was planning to leave as he was signing the contract, Levy and the fans should be thanking him. A long term contract guarantees Spurs an excellent transfer fee.
I don't get why you get so touchy whenever transfers are brought up. Spurs bought him for peanuts, made him a very good player, and during that time he helped them become a very good team. Now, if he leaves, you get a massive transfer fee. Win-win as you has had his services for a while, and then you made a truckload of profits.
We are in a similar situation with De Gea. Came here as a kid, improved massively, and although we pay him a high salary, I wouldn't begrudge him a move to RM. He signed a contract so we would get a handsome transfer fee, and we got to have him for a few years while he was performing at a very high level. If he wants to move to a team that is clearly better, or to a city he prefers, or to get paid more, so be it.