I'll my own off-the-wall comment to the above bizarre comment.
Hypothetically, could unions demand that a carrier make a structural change, like split into two separate carriers?
For example, could unions demand that BNSF undo the last merger and go back to being the BN and ATSF? I heard there were a lot of unhappy union members after the BN merger in ~1970. I don't know all the specifics.
[Sound of Dr. Zarkoff's footsteps coming down the hall.]
I think I know the answer already, but just putting a wild idea out there.