"Every passenger oxygen system installed on our airplanes is tested multiple times before delivery to ensure it is functioning properly, and must pass those tests to remain on the airplane."
This is bullshit. The part that is found to be failing is the release mechanism on the oxygen cylinders. These are a one-time-use pyrotechnic device which, by its design, cannot be tested once installed. So those particular items installed on the aircraft have never been tested. They may have tested others of the same batch, but even that is doubtful.