The very nature of these types of currency is that the seller, the purchaser and the commodity is hidden. The transaction once agreed upon by the parties concerned is invisible and untraceable. I would not bet against it being used by Trump himself for transactions that he wanted unobservable. That's why the bitcoin was conceived. The secretive nature of terrorism would be a good fit with bitcoin except when converted to physical currency. The volatility of the coin would make the exchange rate unpredictable and undependable. I would think that there would be better ways to monitor terrorism. Bitcoin is not a nation state coinage, it is very decentralized and regulated world wide. This would be like put your finger on mercury to hold it still, it ain't done. If the US government wants to try, good luck.