I don't know and I doubt we'll ever know what was happening in his mind. However, what is clear to me is that by forcing the situation, Barnes plan (whatever it was) was disrupted. It may not have been their intention, but by blocking the road, Ranger Anderson and her partner forced Barnes to proceed on foot into the snow without proper gear -- not a good Plan B. Really though, to have a Plan B you need to have a Plan A and what hasn't been established is whether he had any plan at all.

It's sad Ranger Anderson had to die in the process, but this ended about as cleanly as one could expect given prior events and what we presume to be his mindset.