We all know that Bitcoin is also popular to criminals because they can use it without exposing their identity. It will be more convenient to them to use Bitcoin so that they can hide their identity. Do you think that terrorist groups like ISIS use it for their transactions?
I don't think so. The number of chances of ISIS to use bitcoin for their transaction is very minimal. This is due to the reason that in the transaction website, it usually requires some supporting details for identity clarification. Now, if you are being hunted down by some authorities or people who you consider as enemy, would you expose your identity to popular websites? I doubt it.