You do realise that this is a statement from the ATSB report;
The ATSB was unable to ascertain which of the recovery technique(s) was being utilised at the various stages of the spin recovery preceding the accident. For this reason, the ATSB was unable conclude if the use of an inappropriate recovery technique contributed to the accident.
and
Although the reason for the accident could not be fully established, the investigation identified that one of the spin recovery methods that was to be practiced on the day of the accident would most likely not recover the Cessna A150M Aerobat from a spin
Which is important to recognise that we have no conclusive evidence of what exactly caused this accident. The ATSB report is written to highlight the issues withe MB techniques when applied to the A150 and that pilots should seek guidance on a particular type prior to conducting spinning exercises.
I'm not sure what tangent you two are going off on but the important issue here is that spinning an A150 is not straight forward, and even with POH recovery technique the recovery can take time and seem futile until it works. So therefore it is plausible that the instructor may have tried the A150 technique too late in the piece to have recovered or possibly something else complicated the recovery, we just don't know. The briefing is just what the instructor expected to happen, as they were exploring the two generalised spin recoveries, that does not mean he was unaware of the A150 recovery technique, however it is also highly possible he was not etc etc....
Now it is most likely that what was briefed was practiced, that is the MB recovery was demonstrated, didn't work, then the extra time taken to recover led to insufficient height to pull out. But it is just the most plausible scenario, not an actual statement of fact.
On the previous event reported in CYO the correct POH recovery was attempted and the sequence almost ended in the same result, so while its easy to say the MB and PARE did not work, it also seems previously the pilots were almost killed when using the POH recovery. Why is that important? so that anyone who intends to spin A150s should be very cautious about it, and not just feel safe that they are not using the MB technique, lest we end up having the same conversation again when another spin exercise goes wrong. It might be found one day that a particular fuel quantity stabilising in the spin at a specific weight and CoG even within limits might have a nasty bite, who knows.
I was never questioning the ATSB report or its findings.