PFMG,
I understand your argument but we are effectively talking about substitution pay in another form. It's not a case of having a new open scheme for MACr, it's about bums on seats during a manning crisis.
If there are too few AEOs in the system and no facility to commission WSOps as AEOs then surely it is unfair not to offer a substitution package - in the same way as other trades operate.
The MRA4 may be about six years late but PMA had no contingency plan for a delay into service. The cost of raising the PAS threshold to 28 for the MACr AEOs selected would be tiny.