I think your definition is short and very too the point.I am using "targeted" as someone who KNEW Dustin, knew he would be there, and sought out to go harm him.
There could, however, be another component to your definition: or, saw him there.
@mickey2942 has related that the road is a popular camping area for local (well, by Montana standards) tradesmen who work on ultra high end homes in the general vicinity. These tradesmen then return home on the weekends. He goes on to relate that camping is required for tradesmen because though there is plenty of work, there is simply no affordable housing where the work is.
As the victim was a tradesmen as well, perhaps there is a work related motive and an impulsive attack upon seeing the victim in the camping area?