It is doubtful the pilot unions will be able to influence this contract.
The company has the right to dry lease out and wet lease in and the union cannot stop another company such as AEU from recruiting for the A320.
Presumably the EI crews were aware of the T+Cs when they agreed to be seconded, and with the training being conducted by IAGO on behalf of AEU, what training facilities could reasonably be denied?
As often pointed out on this forum, the IPA/F believe in working with airlines not against them, and as such the unions involved are seeing this from dramatically opposed positions.
Whilst this liaison makes sound commercial sense for AEU and increases their standing in the ACMI market, without doubt, it is also an opportunity for the EI management to flex its muscles..