Section 75. No person shall deny or interfere with the right of civil service employees employed by any city or town to petition, individually or collectively, the city or town government or any member thereof, to furnish information to the mayor, city or town manager, city council, or board of aldermen or selectmen or to appear before any committee of such council or boards, or deny or interfere with the right of any civil service employees to petition, individually or collectively, the general court or any member thereof, to furnish information to either branch of the general court, or to appear before any of its committees. This section shall not be construed to authorize an employee who is not on leave to be absent from his employment without permission during regular working hours.