M-B doesn't require two unions. The MOU was crafted by both APA and USAPA to include two concepts. First, that at some point in the process USAPA would cease to be the collective bargaining agent for US Airways pilots and second, once that occurred the provisions and protections of M-B would still apply, i.e., separate representatives would still negotiate and if necessary, arbitrate the SLI.

The fact that USAPA technically doesn't exist doesn't prevent the M-B process, nor impede the SLI. I think the MOU was crafted that way to prevent USAPA from engaging in their obstructionist and self-serving tactics which are known throughout the solar system. USAPA agreed to this, but as usual, Hummel had his fingers crossed behind his back when he signed it and here we are.