To assume that any union can force a management into changing terms of a legally binding document unless they want to is unrealistic.
One should suspect that given the numerous rewrites of bids that have taken place in the past, that what is published is not fact until it happens, if it is not rebid sooner.
Perhaps it would be wise to wait a few days to see what really happens and not run off a cliff. One must also remember that during contract negotiations, many things are said to guage how foolishly the other side will react.
It's always better to wait and keep ones powder dry. Right now, the perimeter is being prodded for weaknesses.
Now is the time to focus on your negotiations and do things that give your team the maximum leverage. Patience is the watchword.