The authority shall require that occupancy of housing projects and residential real property assisted under this act shall be open to all regardless of sex, race, religion, color, national origin, age, marital status, familial status, or disability and that contractors and subcontractors engaged in the construction of housing projects and lending institutions engaged in making residential mortgages, shall take affirmative action to assure an equal opportunity for employment and borrowing. This section does not apply, with respect to the age and familial status provisions only, to the sale, rental, or lease of housing accommodations meeting the requirements of federal, state, or local housing programs for senior citizens, or housing accommodations otherwise intended, advertised, designed, or operated, bona fide, for the purpose of providing housing accommodations for persons 55 years of age or older.