(...) was riding his Segway while walking his dog (...) when he reversed the Segway to allow a fellow dog walker to get past him, he fell from a nearby cliff (...)
Distraction + overconfidence it seems.
Also, had he been on foot, he would have felt the cliff and avoided the accident.
Notoriety isn't just for big-picture stuff. I have a fleeting mention due to a very peripheral involvement in a really big lawsuit, like mentioning the ants when elephants fight.