I'm sorry, the image of one of them wearing a Nazi uniform in my mind makes me think them capable of anything, specifically that thing. I don't think they want to go anywhere. I think they are exactly where they want to be: in an area with lots of aboriginal people. They went to Whitehorse and found it was literally "white" - 3/4 of the population is European origin. So they headed up "north, north, north, Eskimo north" as they used to say, to go find some natives.
Brevik succeeded in his plan because the island he attacked on was so isolated. A reservation is the same thing: one road in, one road out, miles and miles of bush and no help available for hours, even by helicopter.
I feel so sorry for BS's father because he had no clue. He was crying when the two were missing and demanding, "Go find them!" He was aware that his kid was interested in guns (Airsoft), his heritage (Eastern European?), Steam, all that...he just thought it was all innocent. He thought he had a good kid, and cried for him.