Although Yao doesn't have that clouse, he has leverage.

His contract expires next year, and he's a one year player option. Even if Rockets can trade him to any team, but if Yao says he's not going to extend the deal once trades, if he doesn't like the team. No team will trade with Rockets on a one-year loaner. Just like TMac, when he wanted to out of Magic, he picked Rockets among the pursuers. Funny thing is, he was lured by Yao's 41 points against his 37 points in that game.