Nothing contained in this subchapter shall be construed so as to limit, restrict, deny, or affect the coming into or departure from the United States of an alien member of the Armed Forces of the United States who is in the uniform of, or who bears documents identifying him as a member of, such Armed Forces, and who is coming to or departing from the United States under official orders or permit of such Armed Forces: Provided, That nothing contained in this section shall be construed to give to or confer upon any such alien any other privileges, rights, benefits, exemptions, or immunities under this chapter, which are not otherwise specifically granted by this chapter.