That's the same thing GP is saying - nobody reliable, not 'in the game', wants to take the other side of the trade.
(Presumably there is a price at which they do, but also at which nobody's remained interested.)
want vs reality. In fact, I would want to bet against USDT with a reasonable proportion of my savings, but there are no safe way to ensure such a contract will be honored in the case that it actually went to 0.
USDT is super interesting since it doesn't behave like a normal market priced asset. You know it won't ever go up in value, and you know that if it goes down, it goes down to 0 VERY QUICKLY, with maybe a chance of a claim against unverified assets that might pay out after years of litigation.
In past USDT depeg to around 0.9$ for short time. This is very unlikely to be the case since even if they are insolvent they have a reserve.
You probably think that way because of LUNA crash which was backed by almost nothing. For example in defi stablecoins with issues do not depeg to zero or anywhere close to zero if they are still backed to some extent.
Our opinions differ in that you trust Tether's reserve. I don't.
It has been more than 5 years since they were audited. By their own admission, they have 10 billion of their 66 billion dollars in unsecured loans and "other investments".
An org whose entire raison d' etre is to hold money should be pretty open to outside audits. It should actually be a pretty easy audit.
Why have they been foot-dragging so long?
There are no broker that will survive to close the short, and you need a broker to short.