He should be able to leave. He should speak with an experienced immigration attorney before he leaves to evaluate possible options in the future.
Law Office of Luis A. Guerra (954) 434-5800. This answer is of a general nature and should not be relied upon as final, nor is it intended as legal advice.
As long as he has a valid passport from his home country, and a visa of his destination country, if he needs one, he will be allowed to board and leave the U.S.
However, he must be aware that he will not be allowed to return to the U.S. for at least 10 years, even if he would have a basis for a visa.
Until he boards his plane in Atlanta, there is a risk that he may be arrested if he gets into a checkpoint by border patrol.
Wolf W. Kaufmann
Southern California Immigration Attorney
No client-attorney relationship is being created by this posting. Please contact an attorney with questions about your case.