No problem. My first comment was introduced by describing me arriving on the scene.
What were the weather conditions? I have driven that road and many like it numerous times. In fair weather you can often see a long way ahead but if it starts raining hard in that climate visibility can be very reduced.
Not sure if the northbound vehicle was actually passing or in the wrong lane for other reasons, but as you know, passing trucks can be a real challenge on those roads, if they are at near maximum speed, or slowly picking up speed on an incline.
There are also deer and antelope running around in those regions which can create problems if they come out of nowhere. We were in an antelope reserve one time in that general area, never saw one antelope, then a mile outside the fenced boundary, three of them ran across the road just ahead of me. I wasn’t going fast enough for it to be a big problem but I never saw them coming out of the bushes.
Saw half a deer carcass on the I-84 in southern Idaho on another trip, obviously hit numerous times.