The congressional nomination for service academies does not "assist" entrance for those with borderline grades. A nomination (Congress/POTUS/VPOTUS) is part of the application process.
Sorry that was unclear, absolutely recruits must have minimum grades and boards, both of which high minimums. In addition they need a nomination letter, but there is assistance from the academy if the recruit has trouble obtaining one without assistance. The nomination is still required but recruits have a leg up.
