RAT 5, I entirely agree with your sentiments. However as I have been banging on about for some time, it seems Canada DOES allow descent below MDA solely on approach lighting (unspecified) having been visible at DH/MDA, because this will "enable" the flight path to be assessed. Whereas elsewhere (Annex 6 etc) the cues must have been in view for sufficient time for the pilot to HAVE MADE that assessment. That is also (I believe) in the Airbus FCTM - DH/MDA marks the end of any assessment. In Canada you can BEGIN it there. Of course if you then assess it as NOT satisfactory you are in trouble, being below the safe go-around height.
Re the autopilot, not only is the FM limit as already stated by J.O. (MDA-50ft), but "an amber message DISCONNECT AP FOR LDG is displayed when, during a Non Precision Approach, the AP/FD remains engaged at Minimum minus 50 ft, or ‐ 400 ft AGL (if no minimum entered)."
In this case, there is no record of whether the crew entered the MDA in the MCDU. If it was, then it would have been 813' indicated, 790' true, vs the actual MDA of 740'. This message should have come on at the actual MDA, which also ties in with the a 50ft addition to the published MDA when using a CDFA, as in this case. If it was NOT set, it would have come on at 400ft AGL simultaneously with the 400 auto callout, which because of the sloping terrain was actually only about 300ft above the TDZ.
This message should therefore have been visible but there is no record of whether either crew member observed it, and if so made the required callout.