The arbitrage the comment was talking about would be done by people with Circle accounts. If you don't have an account it would be in your interest to sell your USDC for as close to $1 possible. This will inflate the value of USDC on the open market until Circle account holders start to fear that they will be holding the bag.
if major usdc holders who have a circle account were primarily concerned with tiny arbitrage plays they wouldn’t be holding a stablecoin earning zero yield when t-bills pay 5% to begin with
This isn't a tiny arbitrage play because you can repeatedly do it for as long as circle is liquid. Even if you don't hold a lot of USDC it's selling at a discount on the open market. If it goes into a full bankrun all circle accounts will be fighting over what share of the $43.5 billion reserves that they will get.
