Opus,
My guess would be that the retirements were already taken into account thru 1Nov. If not, I can see a definate advantage to the pre-merger Delta side and I'm sure your merger committee would have raised the BS flag on that. I'd lay strong odds that the lists were updated or it would not have been fair. If the arbitrators could not get a Nov 1 list from your committee, then to be fair, they should have used both July seniority lists for the integration.
Denny