In the operation or management of housing projects a commission shall at all times observe the following duties with respect to rentals and tenant selection: (a) it may rent or lease the dwelling accommodations therein only to persons of low income; (b) it may rent or lease the dwelling accommodations therein only at rentals within the financial reach of such persons of low income; (c) it may rent or lease to a tenant dwelling accommodations consisting of the number of rooms, but no greater number, which it deems necessary to provide safe and sanitary accommodations to the proposed occupants thereof, without overcrowding; (d) it shall not accept any person as a tenant in any housing project if the person or persons who would occupy the dwelling accommodations have an aggregate annual net income in excess of any maximum allowed by the federal government pursuant to federal law or regulation in any contract for financial assistance; (e) it shall prohibit subletting by tenants.

   Nothing contained in this section or in section 27 shall be construed as limiting the power of a borrower to vest in an obligee or trustee the right, in the event of a default by the borrower, to cause the appointment of a receiver thereof, free from all the restrictions imposed by this section or by section 27.