I don't know if you're deliberately being silly here or what but it's not one bond purchase and one wire transfer here.
Even with a major primary dealer, they'd have to spread the money around all over the place. Go look at primary dealer stats and offering size stats.
https://markets.newyorkfed.org/api/marketshare/ytd/latest.pdf
https://www.treasurydirect.gov/instit/annceresult/press/preanre/2024/A_20240312_2.pdf
Even a fed primary dealer is only allowed to buy so much of any given offering. One hundred billion is greater than this amount.
I'm not sure you actually understand how big their holdings are. This isn't like buying 100 shares of Apple. If they don't carefully manage what they're doing they will drive the price upwards and overpay.
If their management is ridiculously incompetent I suppose the could just keep wiring money to a broker and never meaningfully review their statements, while providing no price guidance as to what they're willing to pay for bonds, maturities they want, etc.
(I would expect the primary dealer would not accept this, as it would be begging for a lawsuit. I would also expect anybody who is not a moron to refuse to accept instructions from a single employee for $100 billion in assets without confirming those instructions with others.)
You think they just wire a hundred billion dollars from a single account to another account then say what? Buy the maximum 35% of the next few treasury auctions regardless of price. Reinvest in whatever you feel like.
Even if these people have the assets they claim, with the level of staffing they have they are dangerously unsupervised.
And you think that makes it a GOOD idea to give tether your money?
Having the treasury purchases externally managed helps, but it still doesn't really address the staffing question. Even if someone else is doing the buying and selling, they need to provide instructions to the broker and review statements that will have THOUSANDS of treasuries on them at any given moment.
I also have to question the wisdom of having 100 billion in assets at a single broker. Concentration of risk, ability to get the best price, etc.