"It seems like BALPA is offering up junior pilots first for CR."
I the problem with LIFO anyway was that you end up with more people laid off than otherwise would need to be. If the company wishes to save 'X' amount in wages each month then if you reduce your headcount through LIFO it is the lower paid who are out the door first first so you need to cull more of them than if you did reverse LIFO and ushered the most senior (highly paid) staff out.
Wouldnt the union be most interested in saving as many jobs as possible so would fight LIFO on this basis anyway?