The area was first explored by canoe and a lot of people lost their lives when they tried to navigate the river through the canyon. Later during the Cariboo Gold Rush, 1000's of people died on the same river and in the canyon before a primitive road was punched through. Even today, the highway is often closed due to rockslides, snow, avalanches etc. There is no other road through the canyon and the alternative detours are what I mentioned in the original post.

As for bushwhacking, the steep rugged mountains in this region are covered in thick, nearly impenetrable PNW rain forest growth that makes bushwacking for miles and days a non-starter. Even if you could find an alternative route high above and away from the canyon, year round snow on many mountains poses a whole a whole new set of problems. There are number of old and new logging roads, however my maps and Google Earth seraching of the area do not show any that are interconnected along the whole canyon length.

The more I think about it, the better alternative would be to stay put in one of the villages or head back north into less hostile and more open country where there is a much larger population base with better infrastructure and eventual assistance.