This is assuming that the stated 74% number is true. Fool me once...
They aren't claiming to be 99% or 90% backed, which would be similarly disbelieved by the same people who disbelieved the 100% claim.
Also, do they break down the composition of that backing between "cash" and "short-term securities" anywhere, and how many of those "short-term securities" are real assets like T-bills, and how many are unsecured debt that there isn't the money to repay?
74% could be a "real" number ... but it could still be the case that there is only cash to cover 10% of the existing Tethers, and the remaining 64% is loans to companies that can only repay that ten cents on the dollar.