This seems like a great idea. Kind of like OnStar for bikes. I think the idea of giving a delay before the emergency call is sent is fairly simple and elegant. My mind immediately went to false positives before I got to that part of the article.
I see two threads of devices emerging. There are the devices that detect impacts and alert - like these - and the devices that provide personal protection - like airbags for ski avalanche protection. Between the two of them, devices that report accidents and those that protect us, our lives will become a little safer.