One of the real legal questions is whether he lost his “natural born citizen” designation with foreign citizenship...thus having multiple allegiances.
He also probably played the system to get foreign aid for school...that is why he is trying so hard to keep it all quiet.
Eventually this will all come out and most likely they broke laws while covering this up and that is where we will nail them.
That, I think, is the answer in a nutshell. He's a citizen but gamed the system by pretending to be a foreigner to get into college.
You cannot lose something you never had. Natural-born means both parents were citizens.
http://federalistblog.us/2008/11/natural-born_citizen_defined.html
The law is pretty clear on that. One cannot lose one's citizenship based on the actions of others, even one's parents, including by being adopted by a foreign national. In general one cannot even renounce ones own citizenship before the age of 18.
Although "renounce" implies a postive act, it's possible to renounce one's citizenship by entering the US on a foreign passport, representing oneself as a citizen of X, while in the US, and actually being a citizen of X as well of the US. Still another is to serve in the military of X if X is a hostile power.