Craig has been a thorn in the side of the government for some time, first for exposing corruption in the Scottish seats of power, the too-cozy relationships between the judicial and executive branches, and the biased and tainted prosecutions of anyone who gets in their way (including MPs).
The accusations against him hinge on the "jigsaw identification" theory, whereby people could piece together persons from the material he published. The problem is that it's so vague that it could be used against *anyone* who publishes *anything* about a case such as this (and in fact many publications DID publish information that could easily lead to the identification of the accuser, but they were given a pass). This is why he's calling it retribution.
Furthermore, he's been reporting on the Assange case, and that has angered the British government, which is why his appeal was rejected, and why he was not allowed to travel to Spain to give testimony in a case where the Americans were spying on Assange and his lawyer via UC Global.
At this point, Craig's only remaining option is to appeal to the EU court of human rights, but that's gonna be a tough one because he's pissed off the Americans too much with the Assange case.