That's not how I experienced it while testing it. That skill has a 1.5 sec charge up time, in which Hanzo yells some totally bonkers stuff. This is the biggest blinking red light to gtfo, and if you fail to do so, it takes the arrow roughly 2 seconds to kill you (it deals damage per sec, and not a fixed amount on impact). Now you might think that is very little, but when you are already on the run, looking for a way out, 2 sec is not impossible. Also, this teaches players to -not- enter bottlenecks, cause as you said, that is exactly what will happen. People will find a way around it, and it's just gonna be a normal gameplay dynamic.