Here's what I took away from the suggestion. Let's say I send you $100 USDT and Osama Bin Laden sends you $100 USDT. Then you send Justin Beiber $100 USDT and keep the remaining $100 USDT. Where are the tainted tokens?
For Bitcoin these are UTXOs which are easy to trace, but not so for Ethereum and its tokens which just rely on accounting not UTXOs. Right?