Fit to burst
A very short answer to your very valid question. I know several union reps, the majority of the younger ones (that I know) with more than 15 years to go, believe that the proposal is a crock of sh!t.
The older ones (that I know) are split about 50/50.
What you need to remember is only a handful of people (counting both Union and management) have the full picture available to them because of the confidentiality clause that was signed (you can count the number of people on your fingers).
The union reps etc, have had to rely on briefings from the select few from managment and the Union who were privy to the confidential material.
As a Union rep, it is your duty once a decision has been made by the executive, to pass that message on - that's the function of the reps. The union reps are doing this in their official capacity, howerve as I stated above, privately they do not all (by a long stretch) agree with it.