Breivik did tremendous damage to the anti-immigrant cause. Now everyone who stands for Borders, Language and Culture, is unfortunately associated with him.
O offense but he could have been a drugged patsy fed full of rhetoric just to get him to do exactly that, damage the anti immigrant movement by such an act.
Its not like patsies havent been used before to destroy another sides reputation/position. To be then used by the other side, who can claim its no straw man they are referencing. Only a very very small few would know the truth, and they can be controlled or killed as needed.