CP seems much more likely than the terrorist claim.
If there were terrorist blogs--and the Feds had any sense--they'd just force the hoster to give them all the information about who was posting and reading those blogs. It's a whole lot easier to pick off your enemy when you know where they'll be and when they'll be there. They'd get some easy arrests before the terrorists figured out what was up.
With CP all you need are the access logs, no sense in letting the stuff sit around after they've raided all those involved.