And how do they store the private keys of their Bitcoin wallets? They would probably use paper wallets because their phones and computers could be infilitrated easily or could be destroyed. But by using paper wallets, they have the same problem as with fiat money. The paper could be burned through bombs. So, there is no really advantage using Bitcoins over fiat money imho.
If airstrikes are currently targetting buildings where they hold fiat currency, I wouldn't be surprised if they convert part of that money into bitcoin and various other assets.
I don't think news like this makes Bitcoin look particularly bad, Isis probably also converts money into gold etc.
Although, this is yet another shady thing that Bitcoin is connected to..
Their phones are better protected than one would hope. They not only have the phones, but the phone lines, the switches, the cell towers, everything. If the police want your phone in most places they just ask your service provider. In the Islamic state some spook may have a hard time listening in on an encrypted conversation.
Bitcoin is money and money has broad appeal. It really is about wealth and power not bitcoin. In fact the official currency of DAESH is minted in gold, silver, and copper. The image below shows the coins they mint.