They went on a Blister podcast and talked more about the incident and it sounds like the ski strap used was 'perfectly ineffective' as a tourniquet in reducing the bleeding but not cutting off blood flow, cuz his artery hadn't actually been severed and if he'd been tourniqueted properly, he probably would have lost the leg. Which is to say, unless you really know what you're doing and when to use an tourniquet, you should really consider if you should be carrying it.