No labor agreement or contract entered into by a port district shall:
(1) Restrict the right of the port district in its discretion to hire;
(2) Limit the right of the port to secure its regular or steady employees from the local community;
(3) Include within the same agreements: (a) Port security personnel and (b) port supervisory personnel; and
(4) Include within the same bargaining unit: (a) Port professional personnel and (b) port supervisory personnel.