You're missing the point: trading means that you have to find someone willing to do the trade with you. If no one wants to buy your Tethers then you're doomed. Redeeming is completely different - the issuer of your asset has a legal obligation to buy them from you (or at least that's how it should work for assets that aren't scam).
So why not short it against USD? The choice is there on Kraken, it's arguably the easiest win possible if you are convinced USDT will eventually go to zero in the next few years? It's certainly not going to shoot above $1.
