The problem is one of ethics, though: It's one thing to say "I've used it to move money" and "I believe and trust that they have the reserves they claim to have

The problem is one of ethics, though: It's one thing to say "I've used it to move money" and "I believe and trust that they have the reserves they claim to have and I'm willing to hold USDT forever". If you just use USDT as a hot potato, your "calculated risk" is meaningless and you should be calling out that Tether is a fraud.