Looks ridiculous. I suppose if you need to do some machete work, or gollock a zombie across the forehead...
About United Cutlery; most of their stuff is silly, but I just recieved their (stupidly named) "Special Agent Shoulder Harness Knife".
Yes, its for self defense only, and sounds Hollywood, but it's a wicked little knife that's build really good for the 15-30 dollar range. Mine's very sharp, and it's ergonomics and grip make it a really effective fighting implement. I was surprised at its quality.
For a survival knife, though, one would be better served by another company than United.