While I admire your classical musings, they are irrelevant. It is a simple logical deduction for liquidity driven premiums and discounts to exist on assets that are NOT entirely fungible. Tether is NOT fungible back into USD. I can point you towards any number of highly liquid non redeemable ETF's that trade with a basis that is non stationary, or dual listed shares (e.g. China A/H equity classes, worth trillions) which are semi fungible at best due to RMB capital controls, that often trade +/- 5 to 10% 1 sigma away from each other. The fact tether shares many similarities and its basis does NOT move is highly suspicious.
>>"They are confounded that the data (USDT and USD have parity in value) doesn't fit their narrative"
What is your narrative? USDT I agree in principle does have some value, but it certainly doesn't afford to be given the benefit of doubt. In my experience Occam's Razor does not apply to Finance, where the incentive is to employ complexity and opacity to gain any pecuniary advantage possible. I am sure you agree that the set of circumstances Tethers operators find themselves in dealing with unsophisticated counter parties is rich for asymmetric abuse.
Some of the assertions made in the article are misguided; but taking a step back, simply they have produced NO commercially reasonable or acceptable audit of their holdings. Caveat Emptor.