...why would we assume he was ever known as Soetoro?
I do not advocate assuming anything in this regard but, for one, would like to be rid of the foreign student argument if it has no basis.
It is more a hypothesis:
Attending either or both Occidental or Columbia (in whatever sense) as a foreign student, where he would have enjoyed financial benefits courtesy of the taxpayers, would seem impossible if he used the name "O". (We believe he used that name at his high school and at Harvard Law, with the tuition at both paid by private funds.)
I understand we do not have access to school records but if there is other credible evidence of which name he used at either, then one could conclude whether there is substance to the foreign student argument.
Methinks it all depends on WHO you believe him to be. Imo, he didn’t have any need to pose as a foreign student.
http://www.columbia.edu/cu/iraas/projects.html
http://www.columbia.edu/cu/ccbh/mxp/
The doors were wide open...