That's what I thought too. It does let you zip along in narrow spaces, but I kayak in the Intracoastal Waterway and larger fresh water lakes and ponds. Narrow spaces around here are full of aligators, and I've paddled past a few that were longer than my kayak. I was thinking about something like this with a mirror clipped onto my hat so I could see where I was going.
Or an Enginering student, needed something for a Masters Paper.... The Kayak made by Hobie has the bike pedal to propulsion thing sorted out and a long time ago at that...
I had a green one of those paddle kayaks come silently cruising up on me while I was creek bank fishing and I jumped back thinking it was a gator. Years later I did the same thing to a hunter I hadn't seen when I was paddling my green kayak and the poor guy dropped his gun and ran away.