I am a few years older than that guy, and I am trying to imagine how frightening that must have been...
It is one thing to get in the path of an animal and have it kind of go for you, but to have it actively seeking you out, replete with the hooves and the snorts...
Stuff of nightmares for sure.
I saw he was pretty tough, up and moving after surgery and he said after the flip the bison just huffed and puffed and walked away