National Park Service Urges You to Not Knock Down Friends When Charged by a Bear

The old joke goes that, if you're walking with a friend or family member in the woods and are attacked by a bear, you don't have to outrun the bear.
You just have to outrun your friend.
So knock him over or smash his knee, then take off sprinting. The bear will eat your friend instead of you.
The US National Park Service warns against this kind of thinking in a brief Twitter thread . . . but doesn't explain why.
@National Park Service

If you come across a bear, never push a slower friend down…even if you feel the friendship has run its course.⁣⁣

In fact, the NPS has a limited grasp of relationship dynamics.

Doug Jones @Bprtch
Replying to @NatlParkService
What if you're the slower friend?

@National Park Service 

Replying to @Bprtch
Check in on the friendship before you head to the woods.