Breivik saw a threat to European civilization and decided to commit a crime to call attention to the danger to Europe and thereby to avert an even greater evil. That is, he killed 80 people so that a whole civilization might be saved. He was a practical exponent of proportionalist consequentialism. He ignored the moral absolute: you shall not murder.
Similarly the Unabomber and eco-terrorists were so certain that our way of life threatens the planet that they committed crimes to call attention to the danger we are facing. It looks like Ivins saw that the U.S. could be devastated by bioterrorism, and conducted the anthrax attacks to call attention to the danger that Congress was neglecting.
We too often think we understand history, and do wrong so that good may come of it.
But is Edward Abbey responsible for ecoterrorism? Should we not talk about dangers to the environment for fear that it might inspire ecoterrorism? Should we not consider what effect the combination of the demographic winter and Moslem immigration will have on Europe for fear it might inspire people like Breivik?