Attestation reports from BDO Italia state that they hold US Treasuries and that this makes up the core of their holdings.
https://tether.to/en/transparency/#reports
> While the treasury market is large the players are small and no one claims to work with tether.
Even firms like Cumberland who are known to participate in the Tether creation/redemption process do not talk about working with Tether
https://protos.com/tether-minted-usdt-stablecoin-crypto-two-...
For the US Treasury market, the players are not small. Maybe that was believable for the commercial paper dealings for Tether, but you can just directly buy from the US Treasury at auction, or go through a banking partner like Deltec Bank, and none of "the players" will know anything about you.
> You can’t roll billions in treasuries without all the major players knowing who you are.
Of course you can. Direct and indirect bidders for US Treasury bills are routinely in the dozens of billions. No need to go through a primary dealer.
> And if they did they would release their cusips and put this to bed as there is only downside for them by withholding the cusips
Would you honestly be convinced if their attestation reports included CUSIPs? Do you think that people would still clamor for an audit and just move the goalposts to "anyone can look up CUSIPs for US Treasuries. Why aren't the primary dealers confirming their purchases?"