Yep, it's the government's fault. Nothing to do with the companies own decision.
But from the link..
Unions have been able to use these large defined pension funds in a beneficial way for workers over the years to exert political pressure and when these pension funds dry up so will the unions clout. The corporate leaders and their sympathetic political friends know this. Unions and bargaining power could instantly become redundant relative to the past.
It seems their real concern is not for their boomer members well being but the loss of their ability to skim off their members pensions.