In 2002 there was a major fire on the other side of that mountain that burned many acres of beetle-killed trees but it didn’t come down this side. That is old-growth forest and those dead trees near the ridge likely died in a lightning caused fire. Small fires like that are common throughout the forests, especially near the high ridges.
I work with someone who is from Idaho and spent a lot of time outdoors there and in Montana, too, and he shares your love of the area. His family is still up there so he goes back a few times a year and is always excited to go.
Nearly all of the peaks near where I live can be accessed by old trails because in the early 1900’s fire lookout cabins were built on them and the trails to them have been preserved. In the wilderness areas there is access to the peaks but no trails.