The author must not understand basic economics. Cutting out Saturday delivery reduces costs but leaves revenue that same. The same amount of deliveries will still be made in five days instead of six.
This is one of the reasons the USPS was created. In the years leading up to the strike, and then the disaster at Chicago (where mail service ground to a halt) Congress had deferred maintenance costs over and over.
Unless there was a new building where one of their cronies might get a construction contract, most Congressmen didn't care.
Currently USPS is spending more than it gets in revenue. By cutting costs they can bring things into balance.
That, BTW, is what the law requires.