Relative seniority in my opinion, is what Cal's intention was all along. Although the current merger policy does not mention it, relative seniority is the best they could hope for. They are at a disadvantage when considering in total, the three guiding merger principles.
Since the beginning, relative seniority was the consistent theme espoused by the Cal side as fair. Their isl proposal is a long shot at best. If the final construct is essentially relative seniority, they will have succeeded.