Nope. There's not a union in the world that would say no if the company proposal was "eliminate the bottom 5 years of the payscale." If a compressed payscale was desired, it could be had. The problem is that the company proposal is always "eliminate the top 5 years of the payscale."
I'm also not buying your sob story about the ATP rule. It was the fixing of a glitch. So you want to fly a Transport-Category airplane for an Airline? Hmmm... which of these certificates seems most fitting for a person qualified to do that job... if only we had one that was named for that exact situation...
Airline management had a 5 year grace period to fix the problem. The retirement age change gave them 5 years of zero required attrition. That should have been the planning period. The time used to set up a system with which they could attract people to start flight training, and secure a stream of applicants when the old guys start walking out the door. Did they use their time wisely? Nah. More stock buy-backs!!!
I really wish AAG would get it's act together. This isn't sustainable. Many other regional airlines are still able to compete for pilots. Sure, record profits are still a quarterly tradition, but you can't screw your customers over this badly and expect there to be no consequences. If management doesn't roll up their sleeves and get to work soon, I'm slightly concerned about the long-term financial viability of the airline. And I don't just mean Horizon.