But they can do a joint AE before SOC. Lets say they plan on closing the base on Dec 31. SOC that day too, which is the new target date btw. (This one looks better with the Tech Ops issues) They can go and have this AE in DEC with an conversion after SOC. It is ugly but it works.
Or they will have a Displacement on the NWA side, cancel it and then have the AE after SOC. Since they are getting displaced and probably more senior than most, they would go to training first anyway.
Also they may just operate the 742's out of MSP until SOC, then park em and send them to training then. It is not to hard to work around the issue of training more than they have to. It has been thought about.
I am guessing, that based on the info I have, that they will train on whatever they want to. (given that their seniority can hold it, and it is not the 777)