It is not (just) the breathing patterns, but the fact that the crew CAN OPEN THE DOOR with a code if an emergency (like a sudden decompression on the cabin that

It is not (just) the breathing patterns, but the fact that the crew CAN OPEN THE DOOR with a code if an emergency (like a sudden decompression on the cabin that render pilots unconscious) happens. The fact that they could not, and for the voice recording it is obvious they tried, means that the pilot deliberatively blocked the door again for not letting them go in. He also cries before hitting ground.