Ok, I have now read the entire transcript of proceedings at FWA and it appears there is more to this than meets the eye.
The following is a direct quote from the transcript. My bolding
"Mr L Cox: If the tribunal pleases, Cox, initial L, for the Australian Federation of Air Pilots, seeking leave to intervene in the matter. We are a direct party to the award and also there are a number of pilots who are providing specific instructions in this matter."
From this it is reasonable to assume that the AFAP were acting on instructions from their members. It also appears that this ROR agreement was well known about but no one took much notice till it reared its ugly head. The DEC's are obviously AFAP members and asked the AFAP to represent them to enforce the provisions of the ROR agreement. This happened to concur with what management wanted and if you read the transcript you can see why.
When you allow management to tinker with a seniority system this is what can happen.
IMO the ROR should never have been agreed to in the first place. If you are on the bottom and you get sent to Darwin or wherever, you stay there until your number gets you out.
I am not in any way affected so feel free to enlighten me if there are other mitigating factors.