I don't have an answer, but I imagine it would likely have something to do with facilitating money laundering (e.g. lack of banking regulatory compliance), lack

I don't have an answer, but I imagine it would likely have something to do with facilitating money laundering (e.g. lack of banking regulatory compliance), lack of any sort of LE backdoor, or violation of US export law regarding cryptography. Crypto wars have been raging on and off for several decades now. There are so many laws in effect (an unknown number) that under the right political climate, nearly anyone can be imprisoned.