I expected this. Realistically, what they want is quite cheap to provide(as a % of the profits), and the damage they can do by striking is quite significant. All they really had to do was prove that they _would_ strike. A lot of companies try to call the unions bluff, or think of it as MAD where striking hurts both parties.
Also, the ILA demands were reasonable while USMX was making absurd profits while not being reasonable themselves.