I think an important quote is
"A GhostSec member said ISIS’ virtual currency amounts to between 1 percent and 3 percent of its total income – between $4.7 million and $15.6 million. The Treasury Department estimates that ISIS generates between $468 million and $520 million annually. The terror group’s primary sources of revenue are robbery, extortion, oil sales, ransom payments and overseas donations, according to the Treasury Department."
The overwhelming majority of the funds is fiat.
The authority should concentrate on tracking the fiat transaction of the IS, not bitcoin. It will distract its attention.