Tether does offer redemption, but the minimum amount you can redeem is 100,000 USDT, and there is a fee that ranges from 0.1% to 1% depending on the size of the redemption:
So if a well-capitalized arbitrageur can buy a million USDT at a price less than 0.999, they can redeem them for a profit, as long as Tether keeps honoring redemptions.
https://tether.to/en/fees
So if a well-capitalized arbitrageur can buy a million USDT at a price less than 0.999, they can redeem them for a profit, as long as Tether keeps honoring redemptions.