Talked to a buddy yesterday.
Apparently AS does in fact make up the difference (if any) between mil reserve pay and airline pay.
Looks like what this plaintiff is doing is trying to leverage the USERRA provision which specifies that any benefit offered to non-mil leave takers must be afforded to mil leave takers as well.
So Alaska's voluntary and somewhat generous mil pay true up policy is not enough for this guy... he wants full double-dip. Based on the fact that AS somewhat generously offers full pay for jury duty (which typically pays essentially nothing).