You make some very good points which all reminded me of the times when I did a lot of back-country camping and kayaking/canoeing. The furthest north I ever camped was in the Paint Lake (near Thompson) and Grass River areas (you could kayak or canoe all the way to Split Lake if you followed the entire route), but most of my experiences were in the south.
In the south the terrain is also very difficult, but there you're dealing with mostly solid rocky terrain, which is difficult enough to navigate, but it's less boggy and there are lots of rocky but clear areas to escape the near constant dampness of the bush. The thing with the north is that in the bush you are almost always wet or slightly damp at best, and unless you have a way of drying off and especially drying out your socks and footwear, travel and odds of survival definitely decrease over time. Speaking of footwear, they'll also have to have high-quality hiking boots, ideally, more than one pair each that they can rotate wearing. I don't know much about the army style boots BS was seen wearing, but I don't think they'd be appropriate for that terrain.
These two are inexperienced, I don't care how many camp-outs and survival games they played on Vancouver Island, Northern Manitoba with all the swamps, muskeg, dampness and bugs is a different beast altogether. I agree it's possible that they may still be alive if they're still up there) but they won't be for much longer.