“Be aware that many airlines in many parts of the world DO NOT keep their cockpit doors locked, nor are they required to. Too many people confuse those American and British regulations as applying worldwide. They don't”.
Brazil is a contracting member state of a little organization with which you may be familiar; ICAO. The key word is “contracting”, i.e. they have agreed and are contractually obliged to abide by specific agreements. Viz;
ICAO Annex 17: Security: Safeguarding International Civil Aviation Against Acts of Unlawful Interference.
2.1.1 Primary objective of each contracting state is safe guarding its passengers, ground personnel, crew as well as the general public against any acts of unlawful interference.
4.3.3 During flight unauthorized persons must not enter the crew compartment.
5.3.1 States that experienced the act of unlawful interference shall notify ICAO of the security aspects of the interference once the act has been resolved.
13.2.3 In all aircraft that are equipped with a flight deck door (13.2.2 Reinforced Door):
(a) The door shall be kept closed and locked from the time all external doors are closed following embarkation until such time as the external doors are open for disembarkation, except where necessary to permit access to authorized persons and,
(b) Means shall be provided for monitoring from either pilots station the entire door area outside the flight deck to identify persons requesting entry and to detect suspicious behavior or potential threat.