Apparently some are upset that someone wants to leave their sandbox. This is politics at it's worst. Trying to prevent someone from ever re-entering the country again. Such a waste when there is going to be plenty of work to do by years end, with the budget and lots of tax incentives expiring.
http://economy.money.cnn.com/2012/05/17/senators-to-saverin-dont-come-back-ever/?iid=HP_LN