I don't want to debate union positions, but if the company you worked for, wanted to hire another group of workers, to put more money in the company pocket. How would you feel, and what would you do in that situation?
At the least I would understand that the company is in business to make money, not to create or protect jobs, and has a responsibility to its various investors to do so. I would understand that this benefits the customers, the contractors, and a ton of other people through the interconnectedness of an economy, even if it didn't benefit me personally. On those grounds, at least, I would be happy for the company.
When Amtrak tried this it went one step better: nobody was replaced or fired, and it wasn't that more money was going into the company's pocket; the move was to keep money from being drained from the company's pocket. The proposal was leading to a healthier company with better customer service with no harm done to any workers. Everyone was to win... except, I suppose, union power structures who wouldn't be overseeing the new employees.
Anyway, as someone who studies economies and watches as unions very often (no, not every time!) gain at the expense of the companies, customers, and even employees it makes me sad how many union members fail to see the bigger picture, that their benefits come with a cost. The worker versus company mentality encouraged by many union heads seems to blind people to the real situation.