"The lament one reads repeatedly is that they were "unfairly" forced to fund retirement benefits -- though what we're really talking about is retiree medical benefits which the Post Office neither prefunded nor accounted for at the time of benefit accrual, until the 2006 Postal Accountability and Enhancement Act. As reported in The Week in 2018, in an article the title of which ("How George Bush broke the Post Office") makes clear the author's point of view:"

if there's no chance of rescinding these benefits, and the USPS is backstopped by the Treasury, there should be no need to fully pre-fund these liabilities.

"Now, one might point to the private-sector practice of leaving retiree medical liabilities unfunded as justification for doing the same here, so that they sit as an expense item and a balance-sheet liability but don't require any cashflow, but, at the same time, a private-sector company can justify its lack of funding because they can eliminate these benefits at any time; can the Post Office realistically do the same?"

unnecessarily harsh in the execution due to short phase-in period, and additional restriction to invest only in US Treasuries.

"But all this being said, why do I say that Ocasio-Cortez is only "mostly" rather than "wholly" wrong in her statement? Based on private-sector precedents, the 10 year requirement for the plan to fund its retiree liabilities was unusually harsh. In the original 1974 ERISA legislation, plans were given 40 years to fully fund plans that had previously been pay-as-you-go, and 30 years to fund plan enhancements."

"In addition, the retiree medical fund is required to invest exclusively in U.S. Treasuries (see the Postal Service 10-K, page 35-36), and, as a result, the discount rate used in the valuation is considerably lower than a private-sector plan would be obliged to use, in the latter case based on high-quality corporate bonds."

I agree it's difficult to assign malice. but with the modern republican party, it's been borne out that even benign ideas like "addressing election security" are underpinned by malice (to lower voter turnout, in this case). if something smells of malice, what are the odds it isn't?