Notwithstanding any other provision of law, the Secretary of Homeland Security, and the heads of other relevant agencies, shall ensure that personnel who are assigned or detailed to service at the Center shall be considered for promotion at rates equivalent to or better than similarly situated personnel of such agencies who are not so assigned or detailed, except that this subparagraph shall not apply in the case of personnel who are subject to the provisions of the Foreign Service Act of 1980 [
22 U.S.C.
3901 et seq.].