This kind of anonymity makes a "hole" for terorist to keep bitcoin since it's difficult to track it down who the owner of the address.
At my country, still not have a law but it's still not legal as normal payment ( means : use bitcoin with own risk )
Terrorists are not using bitcoin tho and almost no criminals either since bitcoin is so volatile it wouldn't make sense for terrorists to convert 100 million dollars to bitcoin, it would be impossible and extremely risky, it's not going to happen
All darknet markets where you can hire killers, buy drugs, weapons, etc, use bitcoin. So its a main currecy supporting criminal activity in the darknets. Thus why not terrorits? Maybe not good to sent 100 milion, but then to buy guns or probably bombs, require much less money, which can be paid by bitcoin.