Imagine what you would do in this situation. You're a deer (I realize that's a reach) and you're being chased by a coyote. What do you do? If you're in Yellowstone National Park, you hide in a nearby bison herd which is exactly what just happened as a new video shows.
In defense of the driver, I'm not sure what else they could have done. However, they ended up getting too close to a bison in Yellowstone National Park and now they'll have something to explain to the insurance adjuster.
It's hard to impress a bison and not necessarily safe to try. You can ask a group of snowmobilers who just recently traversed Yellowstone National Park in a snowstorm. No, the bison they encountered was not impressed.