By default, BRD_SAFETYOPTION is set to 3. This would prevent the safety switch to be to be activated in flight. However, using “Toggle Saftey Switch” function in MP can bypass the limit and cut all the motor outputs off.
If two drones were connected to one GCS, one drone had just landed and the other was flying. You activated the safety switch of the landed one with MP, and the other one would crash immediately,
because the mavlink command was sent to both drones.