I think it's a mistake to keep this section of trail in the map at all, because it's not just abandoned but obliterated.  The river has completely destroyed that sections of the valley and removed all remnants of there ever having been a path there.

I say this as someone new to OpenStreetMap, so obviously not understanding norms here, but who hikes a lot in the area of this trail and has often seen people getting confused after seeing the route still marked on maps.