For the umpteenth time :
Conditrions for loss of Autopilot :
-THS jam
-THS position lost
-One elevator fault
-Yaw damper actuator lost.
In the above cases, the reversion is to ALTN 1
But for :
-Both engines out
- Double IR fault
-Double ADR fault,
The autopilot will disengage and the law reversion is for ALTN 2.
To go a bit further,the lost protections are :
- Pitch attitude
- High AoA in the case of a dual ADR fault
-Bank angle
- Low energy.
The low speed stability is also lost still in case of a dual ADR fault.
So your ideas about ALTN 1 and low speed stability, etc...etc... are not valid.
To rely on the CMC--> ATSU-->SatCom--> ACARS reception for determining a chain of events is faulty reasoning as the CMC is -if I may - just a snitch reporting on events, computations that have been achieved elsewhere in the systems.