If value from an illicit transaction is ever diverted back into dollars, then it becomes the purview of US officials. I'm assuming that loop had been closed more than once with this mixer.
That's also quite the assertion that anything that happens with dollars is in the "purview of US officials." from a practical perspective you are correct but its conclusion is rather odious. If this were actually true and US dollars are the reason for jurisdiction then we both know launderers would all just use Euro or something else instead 100% of the time. Yet they don't, because pragmatically it makes little differenc as US would pursue their enemies all the same whether they transact in Euro or Dollar -- the dollar in this case is simply an excuse.