The article also acts like changing to a different accounting system in order to get a different result would be the perfect solution. Well, that's how you get underfunded pensions in the first place.
I think the error was in making these pension promises in the first place. It is far better to make promises that you understand how to keep, like the defined contribution of a 401k, than to make promises to your employees that are implicitly assuming a certain rate of investment return for decades.