Repressive Governments Can Own US Companies – Why Not the US Government?

Atrios notes that Saudi Prince Alwaleed bin Talal and China’s government are pumping money into Citigroup. Atrios also reminds us… after 9/11, Rudy Giuliani turned down a donation of $10 million from Alwaleed bin Talal after the latter made statements that seemed to suggest American policies toward the Middle East inadvertently led to the attack.

Its been pointed out by others, but I’d like to ask again… one of the justifications against the Federal government running a surplus (and therefore, one of the justifications put forward by the Fed for justifying GW’s tax cuts) is that if that happens, eventually the US government ends up owning securities like stocks. Why is it such a bad thing the US government, that at least theoretically acts in our best interests, owns a piece of Citibank, but not a problem, and perhaps even commendable that repressive regimes own a piece of Citibank?