Earlier quoted context omitted.
The problem is that it's not that simple to just park $80b on a bank account. The bank will use the money to buy bonds or give it out in mortgages to get interest on it. It's akin to kicking the can to the bank, and getting the money out might fail or be too slow. It's probably better to manage the reserve yourself, to be able to manage risk and liquidity properly, rather than outsource it to a bank.
It sounds like the only way to do this is to create your own bank which directly integrates with the federal reserve.
...but isn't the whole point of Tether to stay as far away from the traditional banking system as they can?
This of course includes avoiding - as much as possible - all the KYC/AML legislation that traditional banks are obliged to follow?